Classical Mechanics
Lecture 1: 1-D Kinematics
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 1, Slide 1
Demo: Inclined Plane w/ Lights and Bowling Ball
Inclined Plane with Lights and Bowling Ball
Description:
Lights on the side of a ramp are placed so that their distance from the starting point
of a ball rolling down the ramp is proportional to the square of the time from when
the ball is released. The lights are all flashed at a frequency determined by the angle
of inclination so that the lights flash when the ball passes over each light.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 1, Slide 2
Classical Mechanics
Lecture 2: Vectors and 2-D Kinematics
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 2, Slide 1
Demo: Cannon on Cart with Tunnel and Pulley
Cannon on Cart with Tunnel (with pulley option)
Description:
A cart is given a push on a
horizontal track and let go. A steel
ball inside its cup is launched
straight up by a spring that is
triggered at a certain point on the
track. The ball demonstrates
independence of X-Y motion by
landing back into the cup on the
moving cart. Due to this X-Y
independence, the ball can jump
over a tunnel placed at an
appropriate spot on the track. A
pulley can also be used to
accelerate the cart. Using this
option, the cart will be going faster
than the ball, and the ball will not
land in the cup.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 1, Slide 2
Demo: Shoot the Monkey
Shoot the monkey
Description:
A stuffed monkey, "Zip", is
shot by a dart aimed directly
at him from an air gun. Even
though he tries to avoid the
dart by jumping from his
tree at the moment that the
dart is launched, Zip gets hit.
This demonstrates the X-Y
independence of the dart's
and the monkey's motion.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 1, Slide 3
Demo: Independence of X-Y Motion
Independence of X-Y Motion (Two Ball Drop)
Description:
There are two small steel balls
on a platform. When the
system is triggered, one ball
falls straight down while the
other is projected horizontally
with a loaded spring. Each one
hits a carefully pre-positioned
metal plate, so that when they
hit, there is a distinct "clink"
that the audience can hear. As
can be heard, the two balls hit
at the same time, and this
shows that the X and Y
components of motion are
independent of each other.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 2, Slide 4
Classical Mechanics
Lecture 3: Relative and Circular Motion
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 3, Slide 1
Demo: Tractor on a Moving Sheet of Paper
Tractor on a Moving Sheet of Paper
Description:
The battery powered tractor
moves along on a sheet of
paper or cardboard. It can be
shown that the tractor's
motion relative to the paper or
cardboard does not vary as the
paper or cardboard is moved.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 3, Slide 2
Demo: Tennis ball on a string with rod
Tennis Ball on a String with Tube
Description:
Begin by spinning the tennis
ball on the string in a circle
pattern. The radius of the ball's
circular path is decreased by
slowly pulling on the string
from the bottom of the tube.
As a result, the ball's angular
speed increases in order to
conserve angular momentum.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 3, Slide 3
Demo: Water in a Bucket
Water in a Bucket
Description:
Put some water in a bucket (fill about 1/4 full) and show that if the
bucket is swung overhead in a circular path fast enough, the water
will stay in the bucket.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 3, Slide 4
Demo: Wine Glass (cup) on Plate
Wine Glass (cup) on Plate
Description:
Holding the string by a hollow
rod, swing the plate with the
cup/wine glass on it in circles.
Centripetal force will keep the
glass on the plate.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 3, Slide 5
Classical Mechanics
Lecture 4: Newton’s Laws
In-class Demos
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 4, Slide 1
Demo: Fire Extinguisher Cart
Rocket Cart (Fire Extinguisher cart)
Description:
The lecturer sits on the cart.
The fire extinguisher is also
attached to the cart, and then
the pin is removed. The cart
plus the lecturer as a system are
propelled in the direction
opposite the escaping gas. This
demonstrates conservation of
linear momentum.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 4, Slide 2
Demo: Table Cloth and Dishes
Table Cloth and Dishes
Description:
Dishes, a candle, and a pitcher are arranged
on a table cloth. The lecturer pulls the cloth
slowly at first, causing the dishes to move
also. Then the cloth is jerked suddenly,
leaving the dishes, candle, and pitcher on
the table. This is a demonstration of
Newton's First Law. Sometimes the lecturer
has the class do a count-down or has a
volunteer pull the cloth from under the
objects.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 4, Slide 3
Demo: Fred the Bear
Fred the Bear
Description:
A bear on
top of a cart
(or Judy)
collides with
an obstacle.
The cart
stops but
the bear
falls forward
due to its
inertia.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 4, Slide 4
Demo: Bow and Arrow
Bow and Arrow
Description:
When we pull back on the bow, the resulting tension can be used to
accelerate the arrow across the room.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 4, Slide 5
Demo: Rotating Al Plate & Dry Ice Pucks
Rotating Aluminum Plate and Dry Ice Pucks on Red Stool
Description:
A frictionless dry ice puck is
given a push along the line
drawn on the plate and
then the plate is rotated.
The puck moves in a
straight line relative to the
floor, but in a spiral relative
to the frame of the rotating
aluminum plate.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 4, Slide 6
Classical Mechanics
Lecture 5: Forces and Free-Body Diagrams
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 5, Slide 1
Demo: Tug of War with Rope on Skateboards
Tug of War with Rope on Skateboards
Description:
Two people pull on opposite ends of a rope in a tug-of-war while also standing on
skateboards. It can be observed that momentum is conserved by comparing their
momentum changes.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 5, Slide 2
Demo: Horizontal Springs
Horizontal Springs
Description:
Various springs attached to a clamp are used to demonstrate properties of springs.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 5, Slide 3
Demo: Springs and Strings in Series in Parallel
Springs and Strings in Series and in Parallel
Description:
A mass is hung from two springs in series,
then in parallel. The springs are stretched
more when the mass is hung in series.
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 5, Slide 4
Demo: Scale on a Skate with Weight(s)
Scale on Skate with Weight(s)
Description:
A spring scale covered with a cloth is
attached to a roller skate. The scale
has one string attached to its support
and another attached to its weighing
hook. The support string is attached to
a clamp and the other string goes over
a pulley and has a hanging mass with
weight W attached to it. Ask the
students to guess what the scale will
read, and then reveal the answer. The
scale is covered again. Next, the
support string is also fitted over a
pulley, and an equal mass with weight
W is hung from it. So there are W
pounds pulling on the right, and W
pounds pulling on the left. What does
the scale read now?
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 5, Slide 5
Demo: Tug of War with Two Spring Scales
Tug of War with Two Spring Scales
Description:
Two spring scales that can be hooked together (for tug-of-war) [tension same no
matter what (scales read the same)]
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 5, Slide 6
Classical Mechanics
Lecture 6: Friction
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 6, Slide 1
Demo: Inclined Plane with Blocks
Inclined Plane with Blocks (Static Friction)
Description:
An adjustable ramp can be set at
different degrees of inclination. A
collection of wooden blocks with
surfaces that have different
coefficients of friction (sandpaper,
waxed paper, etc.) are placed
individually on the incline. When the
ramp reaches the critical angle,
gravity overcomes static friction and
the block begins to slide.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 6, Slide 2
Demo: Static/Sliding Friction Demo
Static/Sliding Friction Demo
Description:
Static friction and sliding
friction are compared
using a sled containing
lead bricks. The sled is
pulled with the scale until
the sled begins to move.
The maximum force
needed to overcome the
static friction and begin
the sled moving is noted.
The sled is then pulled at
a constant velocity and
the kinetic friction
measurement is noted.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 6, Slide 3
Demo: Inertia and the Bicycle Wheel
Inertia and the Bicycle Wheel
Description:
Lecture
demo
showing the
different
points of
inertia with a
bike wheel
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 6, Slide 4
Classical Mechanics
Lecture 7: Work and Energy
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 7, Slide 1
Demo: Timing of Three Falling Objects
Timing of Three Falling Objects
Description:
Three objects (racquetball on
platform, bowling ball
pendulum, and frictionless
cart on a track) are allowed to
fall the same vertical distance
d, while motion sensors
record the time it takes for
each object to fall. These
times should all be the same,
since air resistance will be
negligible.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 7, Slide 2
Demo: Suitcase with Rope and Scale
Suitcase with Rope and Scale
Description:
One end of a 100 N spring scale is attached to a string, and the other end is attached to
a wooden block (suitcase), which can be pulled across the floor by the string as the
scale measures the applied force. With this setup, the lecturer can demonstrate the
difference between static and kinetic friction, and their numerical values. This demo
cannot be done on the lecture room floor the way it currently is.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 7, Slide 3
Classical Mechanics
Lecture 8: Conservative Forces and
Potential Energy
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 8, Slide 1
Demo: Masses on Various Springs
Masses on Various Springs
Description:
Various weights are attached to the ends of
various springs and the resulting oscillatory
motion is observed. The lecturer can then ask the
students about how various properties of the
springs/masses (spring constant, spring length,
mass, etc.) affect various properties of the wave
motion (amplitude, period, etc.).
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 8, Slide 2
Demo: Dry Ice Puck Spring Shot
Dry Ice Puck Spring Shot (conservation of energy)
Description:
A spring with a known spring constant is used to shoot a dry ice puck along a track. The
puck's final velocity is measured to demonstrate conservation of energy, since all of the
spring potential energy (at the beginning) is converted to kinetic energy (at the end).
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 8, Slide 3
Demo: Bowling Ball Pendulum
Bowling Ball Pendulum (conservation of energy)
Description:
A bowling ball, suspended from the ceiling, is
pulled back towards the wall and should
touch the nose of the lecturer. Once released,
the ball will swing back and forth. The lecturer
remains in the same position unscathed upon
the ball’s return to the starting position.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 8, Slide 4
Classical Mechanics
Lecture 9: Work and Potential Energy, P2
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 9, Slide 1
Demo: Roller Coaster
Roller Coaster
Description:
Potential
energy is
converted to
kinetic energy
as the car
rolls down
the track.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 9, Slide 2
Demo: Cork Popper
Cork Popper
Description:
The shaft of an electric motor
is connected to a cylindrical
chamber lined with leather. A
drop of water is placed in the
chamber, and then it is
corked. When the motor is
turned on, the resulting work
done by friction is converted
into heat energy, heating the
water until it evaporates. As
the water vapor heats up
further, it expands and exerts
more pressure on the cork
until the cork finally pops.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 9, Slide 3
Classical Mechanics
Lecture 10: Center of Mass
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 10, Slide 1
Demo: Connected Masses spin on ice table
Connected Masses spin on ice table
Description:
Two masses are connected, and the center of mass is marked. When the lecturer gives
the system a push, the two masses move in such a way that the center of mass can be
seen to move with constant linear velocity. Mass can be added to one side to change
the center of mass.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 10, Slide 2
Demo: Two Pucks on Ice Table; Rotating/Sliding
Two Pucks on Ice Table; One Rotating, One Sliding
Description:
Two identical pucks are pulled along a frictionless table. One puck has a string
attached to its center; the other has a string wrapped around it. The strings run over
pulleys and are attached to weights. When released, the weights pull the pucks with
the same linear acceleration, regardless of where the strings are attached.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 10, Slide 3
Demo: Rubber Pork Chop
Rubber Pork Chop
Description:
The painted white dot shows where the center of mass of the pork chop is. The pork
chop is thrown and students observe the parabolic behavior of its center of mass, no
matter how the chop is thrown.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 10, Slide 4
Classical Mechanics
Lecture 11: Conservation of Momentum
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 11, Slide 1
Demo: Inelastic Collision on Air Track
Inelastic Collision on Air Track
Description:
An object is sent along the air track at a given velocity. It collides with another object
further along the track. The two then stick together and continue along the track
together, showing an example of an inelastic collision.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 11, Slide 2
Demo: Ballistic Pendulum w/ clay ball and block
Ballistic Pendulum with clay ball and block
Description:
A clay ball is thrown at the side of a block which is covered in nails. The ball sticks and,
due to conservation of momentum, the ball and box swing together in the direction
that the ball was originally going. The amplitude of the resulting oscillation is
measured and used to calculate the original speed of the clay ball.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 11, Slide 3
Demo: Happy Ball and Sad Ball
Happy Ball and Sad Ball
Description:
Both balls are dropped. Upon hitting the floor, one bounces and the other does not,
due to the different coefficients of restitution of their materials.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 11, Slide 4
Demo: Super/Clayball Pendulum Block of Wood
Super/Clayball Pendulum with Block of Wood
Description:
We have two pendula, one of clay, and one
with a super ball. Each one is pulled back to
the same height, and let to hit a block of
wood which stands on the table. The
superball bounces back higher, so the
momentum that it transfers to the block is
greater than in the case of the clay ball.
Thus, the block that the superball hits will
fall down while the other block will remain
standing.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 11, Slide 5
Classical Mechanics
Lecture 12: Elastic Collisions
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 12, Slide 1
Demo: Elastic Collision on Air Track
Elastic Collision on Air Track
Description:
Two carts on an air track collide head-on and each moves in the opposite direction
from which it came, showing the students a simple example of an elastic collision.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 12, Slide 2
Demo: Newton's Cradle
Newton's Cradle
Description:
The lecturer usually begins by taking one ball, raising it away from the others, and then
releasing it to collide with its neighbor. The momentum of the ball is transferred
through the system, and the ball on the other end reacts accordingly. The lecturer can
then repeat the process with two balls, or three, or four. This demonstrates
conservation of momentum in a collision involving several bodies.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 12, Slide 3
Demo: Glancing Collisions
Glancing Collisions
Description:
Two magnetic, frictionless (dry ice) pucks are pushed towards each other, while on the
gridded table, to cause an elastic or inelastic collision. The lecturer can show how the
different incident angles can affect the final trajectories.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 12, Slide 4
Classical Mechanics
Lecture 13: Collisions, Impulse and
Reference Frames
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 1
Demo: Basketball Drop with Small Ball on Top
Basketball Drop with Small Ball on Top
Description:
When a basketball is dropped
alone, it bounces a certain
height. When a smaller ball is
dropped alone, it bounces a
certain height. If the smaller
ball is placed on top of the
basketball, and they are
dropped simultaneously, the
small ball bounces significantly
higher than it would if
dropped alone.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 2
Demo: Basketball Drop with Small Ball on Top
Basketball Drop with Small Ball on Top
Description:
When a basketball is dropped
alone, it bounces a certain
height. When a smaller ball is
dropped alone, it bounces a
certain height. If the smaller
ball is placed on top of the
basketball, and they are
dropped simultaneously, the
small ball bounces significantly
higher than it would if
dropped alone.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 2
Demo: Collision of Bowling Ball and Golf Ball Pendula
Collision of Bowling Ball and Golf Ball Pendula
Description:
Students observe the collision of a
comparatively small mass (the golf ball) with a
large mass (the bowling ball) to see how linear
momentum is conserved.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 3
Demo: Bed Sheet with Raw Eggs
Bed Sheet with Raw Eggs
Description:
When we throw an egg
against a held sheet, the
momentum of the egg is
reversed by the force on
the egg by the sheet, but
the sheet 'softens the blow'
in that the force takes place
over a longer period of time
than if the egg were to be
thrown at a heavy and rigid
fixed object like the wall or
the floor. Because the
collision is longer in
duration, the maximum
force applied to the egg is
small enough that the egg
does not break.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 4
Demo: Rubber Pork Chop
Rubber Pork Chop
Description:
The painted white dot shows where the center of mass of the pork chop is. The pork
chop is thrown and students observe the parabolic behavior of its center of mass, no
matter how the chop is thrown.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 5
Demo: Ball Bearings Drop
Ball Bearings Drop
Description:
A metal tube is filled with 228 ball bearings, and then the tube is tipped such that they
are dropped from above a scale. When they hit the scale's platform, the average
weight registered on the scale is a measure of the pressure exerted on it by the falling
ball bearings. This is a large-scale model of what happens when pressure is caused by
individual molecules hitting the walls of a container.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 13, Slide 6
Classical Mechanics
Lecture 14: Rotational Kinematics and
Moment of Inertia
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 14, Slide 1
Demo: Inertia Rods
Inertia Rods
Description:
One of these rods has most of its mass in the center, and the
other one has most of its mass out at a larger radius. Hence, the
first rod will have a smaller moment of inertia about its
perpendicular axis, and it will take less torque in order to rotate
it. The students should take turns feeling this effect for
themselves.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 14, Slide 2
Demo: Phasor Wheel
Phasor Wheel
Description:
Magnetic arrows are
placed on a round
blackboard, which is
hung vertically and
then spun. This can
be used to
represent the
direction of the
instantaneous
velocities and
accelerations at
various points on
the circle.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 14, Slide 3
Demo: Different Weights on Rotating Stool
Different Weights on Rotating Stool
Description:
The lecturer (or a volunteer) sits on the
spinning stool. With the weights (one in
each hand), the person can change their
moment of inertia. If they hold the weights
with arms fully extended, they have a large
moment of inertia, and will rotate slowly. If
they bring the weights in towards the
center, they reduce the moment of inertia,
and begin to rotate faster due to
conservation of angular momentum.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 14, Slide 4
Demo: Tennis Racket and Ball Collision
Tennis Racket and Ball Collision
Description:
An example of an imperfect elastic
collision. No macroscopic collision
is perfectly elastic. Although the
shapes of the tennis ball and
racquet are apparently restored
after the ball is dropped on the
racquet held fixed, the ball won't
rise to the same height from which
it was dropped. This shows that
energy was not conserved in the
collision and so the collision was
not perfectly elastic
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 14, Slide 5
Demo: Hula Hoop with Arrow
Hula Hoop with Arrow
Description:
Visual aids used to show the direction of current.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 14, Slide 6
Classical Mechanics
Lecture 15: Parallel Axis Theorem and Torque
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 15, Slide 1
Demo: Roll Different Objects Down Incline Plane
Roll Different Objects Down Incline Plane
Description:
The lecturer rolls a variety of objects down the incline plane, allowing for the
comparison of angular accelerations. The students can see which properties (mass,
radius, moment of inertia) affect these accelerations by "racing" similar objects down
the incline.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 15, Slide 2
Demo: Big Wrench and Stuck Bolts
Big Wrench and Stuck Bolts
Description:
The longer the lever (handle on the wrench), the easier
it will be to loosen the bolts and to apply the same
torque. This is because torque is equal to (length of
wrench) x (force applied).
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 15, Slide 3
Demo: Hula Hoop with Arrow
Hula Hoop with Arrow
Description:
Visual aids used to show the direction of current.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 15, Slide 4
Demo: Rubber Pork Chop
Rubber Pork Chop
Description:
The painted white dot shows where the center of mass of the pork chop is. The pork
chop is thrown and students observe the parabolic behavior of its center of mass, no
matter how the chop is thrown.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 15, Slide 5
Demo: Inertia and Bicycle Wheel
Inertia and Bicycle Wheel
Description:
Lecture demo showing the different points of inertia with a bike wheel
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 15, Slide 6
Classical Mechanics
Lecture 16: Rotational Dynamics
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 16, Slide 1
Demo: Roll Different Objects Down Incline Plane
Roll Different Objects Down Incline Plane
Description:
Two carts on an air track collide head-on and each moves in the opposite direction
from which it came, showing the students a simple example of an elastic collision.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 16, Slide 2
Demo: Atwood’s Machine: Weight and Pulley
Atwood’s Machine: Weight and Pulley
Description:
The Atwood's Machine
consists of masses which
hang on pulleys. A string
on a given pulley will
always have the same
tension on each side.
Hence, if we put the same
mass on each side, they
will not accelerate up or
down.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 16, Slide 3
Demo: Sliding to Rolling Transition of a Bowling Ball
Sliding to Rolling Transition of a Bowling Ball
Description:
A bowling ball is
slid along the
floor and the
motion detected
by the motiondetector is
displayed
graphically on
the computer.
We can then use
the resulting
data to
determine the
speed at which
the ball will
begin to roll.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 16, Slide 4
Classical Mechanics
Lecture 17: Rotational Statics: Part I
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 17, Slide 1
Demo: Suspended Static Beam
Suspended Static Beam
Description:
The beam is
suspended from
two scales which
measure force.
The lecturer can
hang different
objects from the
hooks on the
beam, to show
how the net
force/torque
acting on the
beam must equal
zero.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 17, Slide 2
Demo: Static Truck on Incline
Static Truck on Incline
Description:
A truck on a 30 degree
incline is held in static
equilibrium by masses
hung over two pulleys.
After the lecturer pulls
the incline out from
under the truck, the
truck does not move.
This shows that the
masses keep the
system in static
equilibrium. The sum
of the external forces
in both the X and the Y
directions add up to
zero.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 17, Slide 3
Classical Mechanics
Lecture 18: Rotational Statics: Part II
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 1
Demo: Ladder Leaning Against Wall
Ladder Leaning Against Wall
Description:
A ladder, with wheels on both ends and a chain attaching
its center to the blackboard, leans against the wall. When
someone stands on the ladder, a scale on the wall
measures the extra downward force of the person's
weight. We can then compare to the measured weight
using a bathroom scale (on the ground).
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 2
Demo: Floating Object (Static Equilibrium)
Floating Object (Static Equilibrium)
Description:
For equilibrium, the string force must be vertical since the only other forces, gravity
and buoyant force, are also vertical.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 3
Demo: Solar System Model
Solar System Model
Description:
This is a model of the solar system and its orbits.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 4
Demo: Tweetie Eagle
Tweetie Eagle
Description:
The eagle is weighted such that it will balance on it's beak, due to its center of mass.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 5
Demo: Balancing Bottle and Block of Wood
Balancing Bottle and Block of Wood
Description:
A specially cut block of wood and a glass bottle are used to demonstrate the
importance of finding center of mass. The wood alone will not stand on this slanted
edge because the wood's center of mass is not supported by the base. The bottle is
carefully placed in the hole in the wood. This new system of objects will balance
because the center of mass of the system is now properly supported.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 6
Demo: Hammer on Hinged Board
Hammer on Hinged Board
Description:
For equilibrium,
the string force
must be vertical
since the only
other forces,
gravity and
buoyant force,
are also
vertical.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 18, Slide 7
Classical Mechanics
Lecture 19: Angular Momentum
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 19, Slide 1
Demo: Drop Wheel Rim on Rotating Wheel Rim
Drop Wheel Rim on Rotating Wheel Rim
Description:
A car wheel rim is mounted on an axle. A similar rim is mounted above it but held up
with a rope such that it does not come into contact with the lower rim. The lecturer
spins the bottom wheel and times its period. The rope holding the top rim is then
burned, causing it to fall onto the rotating rim. The new period is measured. The ratio
of the moments of inertia can be calculated.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 19, Slide 2
Demo: Medicine Ball on Rotating Stool
Medicine Ball on Rotating Stool
Description:
The lecturer sits on the spinning stool. A
volunteer hands the ball to the spinning
lecturer. The lecturer holds the ball at arms
length. The moment of inertia of the lecturer
is increased when holding the ball, and so
the stool turns more slowly. If the lecturer
brings the ball closer, their moment of inertia
decreases, and the stool rotates faster. This
demonstrates conservation of angular
momentum.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 19, Slide 3
Demo: Train on Bicycle Wheel
Train on Bicycle Wheel
Description:
Mount a track for a toy train onto a horizontal bicycle wheel, which is free to rotate. If
we put the train onto the track and then run it with the motor, then the track/wheel
combination will react by rotating in the opposite direction, thus conserving angular
momentum.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 19, Slide 4
Demo: Different Weights on Rotating Stool
Different Weights on Rotating Stool
Description:
The lecturer (or a volunteer) sits on the
spinning stool. With the weights (one in each
hand), the person can change their moment
of inertia. If they hold the weights with arms
fully extended, they have a large moment of
inertia, and will rotate slowly. If they bring
the weights in towards the center, they
reduce the moment of inertia, and begin to
rotate faster due to conservation of angular
momentum.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 19, Slide 5
Classical Mechanics
Lecture 20: Angular Momentum Vector and
Precession
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 1 Demo: Circular Ice Table with Hanging Weight
Circular Ice Table with Hanging Weight Descrip)on: A large circular aluminum ice table with a rotatable pulley in the center allows a string to be a=ached from the dry ice puck to a mass (mass m) below. The lecturer rotates the puck (mass M) at a radius, r, and uses a Dmer to determine the velocity. (MV^2)/r for the puck can be compared to (m*G) for the different hanging masses. Demonstra@ons © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 2 Demo: Precession of Gyroscope using Bicycle Wheel
Precession of Gyroscope using Bicycle Wheel Descrip)on: The bicycle wheel gyroscope appears to defy the laws of gravity as it balances on a single point (like shown). Begin with the wheel staDonary, hanging from the rope. Then as the lecturer rotates the wheel, it's axis of rotaDon precesses, causing it to Dlt upwards. Demonstra@ons © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 3 Demo: Rotating Stool with Bicycle Wheel
Rota)ng Stool with Bicycle Wheel Descrip)on: While the lecturer is spinning on the rotatable stool, a volunteer hands him/
her a rotaDng bicycle wheel. Holding the wheel at different angles will either increase or decrease the angular velocity of the lecturer on the stool due to conservaDon of angular momentum. The person on the stool can increase his/her velocity by handing off the spinning wheel to a staDonary person and then taking it back aSer a full rotaDon (the staDonary person flips the rotaDng wheel over before handing it back to the person on the stool). Demonstra@ons © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 4 Demo: Different Weights on Rotating Stool
Different Weights on Rota)ng Stool Descrip)on: The lecturer (or a volunteer) sits on the spinning stool. With the weights (one in each hand), the person can change their moment of inerDa. If they hold the weights with arms fully extended, they have a large moment of inerDa, and will rotate slowly. If they bring the weights in towards the center, they reduce the moment of inerDa, and begin to rotate faster due to conservaDon of angular momentum. Demonstra@ons © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 5 Demo: Gyroscopes
Gyroscopes Descrip)on: Gyroscopes are used to demonstrate the moDon (precession and nutaDon) of the axis of a rotaDng rigid body when a net torque is acDng on it. Demonstra@ons © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 6 Demo: Metersticks with Arrows
Meters)cks with Arrows Descrip)on: Demonstrate electric fields with metersDcks with arrows Demonstra@ons © Dept. of Physics, Univ. of Illinois at Urbana-­‐Champaign, 1996 Mechanics Lecture 20, Slide 7 Classical Mechanics
Lecture 21: Simple Harmonic Motion
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 21, Slide 1
Demo: Mass on Spring
Mass on Spring
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 21, Slide 2
Demo: Bowling Ball Pendulum
Bowling Ball Pendulum
Description:
A bowling ball, suspended from the
ceiling, is pulled back towards the wall
and should touch the nose of the
lecturer. Once released, the ball will
swing back and forth. The lecturer
remains in the same position unscathed
upon the ball’s return to the starting
position.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 21, Slide 3
Demo: Simple Harmonic Motion
Simple Harmonic Motion
Description:
The harmonic oscillation of a spherical mass
on a spring and the circular motion of a
motor-driven mass are compared. The
shadows on the screen move up and down
in sync.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 21, Slide 4
Demo: Cart Attached to Inclined Track
Cart Attached to Inclined Track
Description:
When the cart is pulled
down the ramp and
released, it has a distancedependent force acting on
it, which causes the system
to exhibit simple harmonic
motion.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 21, Slide 5
Classical Mechanics
Lecture 22: Simple and Physical Pendula
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 22, Slide 1
Demo: Bowling Ball Pendulum
Bowling Ball Pendulum
Description:
A bowling ball, suspended from the
ceiling, is pulled back towards the wall
and should touch the nose of the lecturer.
Once released, the ball will swing back
and forth. The lecturer remains in the
same position unscathed upon the ball’s
return to the starting position.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 22, Slide 2
Demo: Physical Pendulum
Physical Pendulum
Description:
This is an odd-shaped rigid body
which can be suspended from
different points along its edge.
When it is displaced from its
equilibrium position, it will
oscillate back and forth. Then
the lecturer can show that this
method can be used to find the
effective distance from the
point of suspension to the
center of mass.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 22, Slide 3
Demo: Physical Pendulum vs. Simple Pendulum
Physical Pendulum vs. Simple Pendulum
Description:
The beam is suspended from two scales which
measure force. The lecturer can hang different
objects from the hooks on the beam, to show how
the net force/torque acting on the beam must
equal zero.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 22, Slide 4
Demo: Torsion Pendulum
Torsion Pendulum
Description:
This is a torsion pendulum that has red
spheres attached to it, to make the
oscillations easier to see.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 22, Slide 5
Demo: Hula-Hoop Pendulum vs. Simple Pendulum
Hula-Hoop Pendulum vs. Simple Pendulum
Description:
The lecturer demonstrates that the hula-hoop
pendulum behaves like a simple pendulum with a
length equal to the diameter of the hula-hoop.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 22, Slide 6
Classical Mechanics
Lecture 23: Harmonic Waves & Wave Equilibrium
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 23, Slide 1
Demo: Torsion Wave Machine
Torsion Wave Machine
Description:
Steel rods are evenly
connected, at their
centers, to a wire
which is supported
above a metal
triangular base. When
a rod, or group of rods,
are displaced upwards
or downwards, the
wave propagates and
then dies out. If there
is a damper placed at
one end, some of the
initiated wave is
reflected back.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 23, Slide 2
Demo: Transverse Wave on Rope
Transverse Wave on Rope
Description:
A truck on a 30
degree incline is held
in static equilibrium
by masses hung over
two pulleys. After the
lecturer pulls the
incline out from
under the truck, the
truck does not move.
This shows that the
masses keep the
system in static
equilibrium. The sum
of the external forces
in both the X and the
Y directions add up to
zero.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 23, Slide 3
Demo: Transverse Wave Machine
Transverse Wave Machine
Description:
This hand-cranked apparatus can be set
up so that its shadow is projected onto
screen behind it. The apparatus shows
a model of the movement of transverse
waves and longitudinal waves, and
shows their similar behavior.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 23, Slide 4
Classical Mechanics
Lecture 24: Waves and Superposition
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 24, Slide 1
Demo: Standing Wave Machine
Standing Wave Machine
Description:
Produce a standing wave in a string by fixing one end, and then attaching the
other to a mechanical vibrator. The lecturer can adjust the frequency such
that clear nodes and antinodes can be seen by the class. Then, using the
strobe light, show a "snapshot" of the standing wave at any point in time.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 24, Slide 2
Demo: Beat Frequencies
Beat Frequencies
Description:
The frequencies of the two function generators are adjusted so that you can hear
clear beats from the interaction of the pitches that are coming from the speakers.
The oscilloscope can be used to display the resultant waveform of the beats.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 24, Slide 3
Demo: Standing Waves on Long Spring
Standing Waves on Long Spring
Description:
An audience
volunteer holds one
end of the spring
and the lecturer can
set up different
standing waves in
the spring while the
volunteer holds
their end stationary.
Alternate: Use a
clamp and a pole
instead of a
volunteer.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 24, Slide 4
Demo: Wooden Whistle with Helium and Air Pump
Wooden Whistle with Helium and Air Pump
Description:
The densities of gases are shown with a
wooden whistle. Helium from a tank and
normal air from a pump are blown through
a wooden whistle, one at a time. The
sounds made by the different gases are
compared.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 24, Slide 5
Classical Mechanics
Lecture 25: Fluid Statics
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 1
Demo: Hydraulic Lift Model
Hydraulic Lift Model
Description:
Two syringes of
different diameters are
connected by plastic
tubing. When the
plunger of the larger
diameter syringe is
pushed a small
distance, then the
plunger of the smaller
diameter syringe rises
a larger distance.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 3
Demo: Pascal’s Vases
Pascal’s Vases
Description:
Several differently
shaped vases are all
connected at the
bottom, and fluid is
put into all of them.
Since atmospheric
pressure is the same
in each vase, the
fluids will seek their
own level, no
matter what the
shape of the
container.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 4
Demo: Density of Water vs. Alcohol
Density of Water vs. Alcohol
Description:
Ice floats in water because it is
less dense than the water. In
alcohol, however, the ice sinks
due to its relatively greater
density.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 5
Demo: Archimedes’ Principle
Archimedes’ Principle
Description:
2 setups: one with the mass hanging
from a double pan balance and the
other with various masses hanging
from a spring scale. In both cases, the
weight of the hanging masses can be
measured in air and then also when
submerged in a beaker of water. The
differences in the measurements give
the buoyant forces of the water on the
masses and can be compared to the
weight of the water displaced by the
respective masses.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 6
Demo: Floating and Sinking Pop Cans
Floating and Sinking Pop Cans
Description:
The diet pop floats while the regular sinks due to the difference in densities
of the liquids.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 7
Demo: Magdeburg Hemispheres
Magdeburg Hemispheres
Description:
The Magdeburg Hemispheres fit together around the rim to form a sphere. There is a
valve on one of the hemispheres. A vacuum pump is hooked up and the air is pumped
out of the sphere. Since the atmospheric pressure is now so much greater than the
pressure within, this pushes the hemispheres together, and it requires a very large
force to pull the hemispheres apart. If the valve is opened, air rushes in, and they
separate easily.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 8
Demo: Crush Tin Can with Vacuum Pump
Crush Tin Can with Vacuum Pump
Description:
A tin can is sealed and the air is
pumped out of it with a vacuum
pump. The can is then crushed by
the atmospheric pressure
pushing in on it.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 9
Demo: Surface Tension of Water
Surface Tension of Water
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 25, Slide 10
Classical Mechanics
Lecture 26: Fluid Dynamics
In-class Demonstrations
Demos © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 1
Demo: Charles’ Law
Charles’ Law
Description:
A glass jug (filled with air)
is attached to a U-tube,
which is filled with a
bright yellow liquid
(which will be easy to see
by a large audience).
Change the temperature
of the air inside the jug by
placing it first in a bath of
cold water, and then in a
bath of hot water. Notice
how the volume of the air
increases or decreases
depending on
temperature, by looking
at the level of the liquid
in the U-tube.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 2
Demo: Venturi Tubes
Venturi Tubes
Description:
This three tube model demonstrates the
relation between flow speed and pressure.
This can be observed by watching the
levels of the liquid in the venturi tubes, and
how it relates to the flow speed of the
water in the larger tube.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 3
Demo: Head Pressure Demo
Head Pressure Demo
Description:
A tall tube has holes in it,
equally spaced up and down the
tube, but all aligned on one
side. If we fill the tube with
water and then let it drain out
the holes, the flow rate at each
hole will be different, due to the
different pressure at each
location. Thus, we can see that
the water will shoot farthest out
the bottom hole.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 4
Demo: Balance Objects on Air Jets
Balance Objects on Air Jets
Description:
This demonstration shows the importance of Bernoulli's Principle in keeping the
ball from falling to the ground. The quickly moving air acts as a buoyant force on
the ball, opposing gravity and keeping the ball stationary.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 5
Demo: Bernoulli’s Pop Cans on Straws
Bernoulli’s Pop Cans on Straws
Description:
Blow air through a straw in between cans and the cans are drawn together.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 7
Demo: Vacuum Cannon
Vacuum Cannon
Description:
Pressure differential between atmosphere and vacuum creates enough force to
accelerate a ping pong ball thru the length of a tube to a speed high enough to
pierce an empty soda can on impact.
Demonstrations © Dept. of Physics, Univ. of Illinois at Urbana-Champaign, 1996
Mechanics Lecture 26, Slide 8