Topic: Forces and Motion
Aim: How do you get an object to start moving?
Do Now: Complete question # 3 on back of the KE
and PE packet.
HW:CL Waves due Thursday
Reading Notes – Newton’s Laws
Energy and Waves Exam on Tuesday
At which two points on the pendulum, is the
pendulum experiencing the greatest potential
energy?
Identify the two processes below. Support your
answer.
Which of the following electromagnetic
waves have the highest frequency?
1. Visible light
2. Ultraviolet light
3. Microwaves
4. Infrared waves
Identify the statement that is true based of the
electromagnetic spectrum.
1. Microwaves are shorter then X-rays.
2. Infrared rays are longer than gamma waves.
3. Radio waves are longer than visible light waves.
4. UV waves are longer than visible light waves.
5. Visible light rays are shorter than microwaves .
6. Red rays have a shorter waves that violet rays.
Which type of EW are used in medical technology
because they can pass through parts of the human
body?
1. Microwaves
2. X-rays
3. Infrared waves
4. Ultraviolet radiation
Force
•
•
•
•
A push or a pull
Newtons = N
Gives energy to an object
Move , stop, or change
direction
Work:
• F xd
– F = force applied
– D = distance the object moved
• Work is done when force causes
motion.
Inertia
• An object’s resistance to
change in motion
What causes the force of inertia?
• Combination of gravity pulling down on an
object and friction resisting a push ahead
The body is motionless at the start
of a race. The athlete must overcome
their inertia to start moving!
•
Motion
is
caused
by
Unbalanced
a
greater
force
Forces
(Unequal)
Balanced • No motion occurs
Forces
(EQUAL)
Friction • Force that resists the
relative motion of 2
bodies in direct contact
• Acts opposite to motion
of moving object
• Causes moving object to
slow down & stop
•Generates heat
Lubricant: Slippery substances
• Oil or grease
• Decreases friction
ICE = very slippery =
–DECREASES friction
• STICKY SURFACE = hard to
move
–A lot of friction
Examples:
1. Gymnasts use chalk on hands to
increase friction.
2. Cyclists rely on friction to hold
their bikes on the ground during
turns.
3. Without friction cars would
not be able to stop.
Why is water being added to the slip
& slide? What would happen if water
was not added?
The driver of the car applies the brakes to avoid
hitting the cow. But how does this cause the car to
slow down and stop?
The brakes cause the wheels to stop turning and to slide on
the road surface. This action produces a force that resists
the forward movement of the car. This force is called
friction.
25N
15N
25N + 15N =
40N
to the right
25N
15N
25N - 15N =
10N
to the left
10N
10N
10N
5N
Let’s summarize…
1. Describe force.
2. Describe work.
3. How do you know when work is done?
4. Explain the difference between balanced and
unbalanced forces.
5. Describe friction.
6. What kind of surface will decrease friction? Increase
friction?
7. How do you calculate total force when applying force
on an object in the same direction?
8. How do you calculate total force when applying force
on an object in the different directions? Which way
will the object move?
Bw 2 rarefactions
Bw 2 compressions
Describe a wavelength in a longitudinal wave.
The distance between 2 compressions OR 2
rarefactions.
C
B
AA
to keep track of units in multi-step conversion
problems
D
Identify the parts of this transverse wave. (Click to
uncover the answer of each letter)
1. Which wave
has the highest
frequency?
A
C
2. Which wave has
the longest
wavelength?
A
B
C
Consider a cart on a horizontal frictionless table. Once the
cart has been given a push and released, what will happen to
the cart?
1.
2.
3.
4.
5.
slowly come to a stop
continue with constant acceleration
continue with decreasing acceleration
continue with constant velocity
immediately come to a stop
A test paper is sitting at rest on your desk. Which of
the following statements best describes this
situation?
1. There are no forces acting on your paper.
2. Your paper is at rest in any coordinate system.
3. Your paper exerts no force on the desk.
4. There are several forces acting on your paper, but
they balance each other out.
A 2 ton elephant is balancing on a tree trunk. Which
of the following statements is accurate?
1. The weight of the tree stump is greater than 2
tons.
2. A 4 ton force on the ground spreads out in all
directions.
3. The tree stump is exerting a 2 ton force upward on
the elephant.
4. The downward force on the ground under the tree
stump is 4 tons.
A hot air balloon exerts a force of 1200N while lifting
a load of 800 N. Which free-body force diagram
depicts the forces involved?
400N
1.
800N
800N
1200N
2.
3.
1200N
800N
800N
4.
400N
A student is riding a bike and applies
the brakes. What most helps the bike
to stop?
1. Friction
2. Heat
3. Gravity
4. Momentum
2 people are pulling at opposite ends of a
rope. If they are pulling on the rope with
equal but opposite forces, what will
happen to the rope?
1. It will stay in place between the 2
people.
2. It will move towards the right.
3. It will move towards the left.
4. It will fall to the ground.
2 people are pulling at opposite ends of a rope.
The person pulling on the right side of the rope is
applying a force of 50N while the person on the
left is applying a force of 70N. What will happen
to the rope?
1. It will move towards the right.
2. It will move towards the left.
3. It will fall to the ground.
4. It will stay in place.
Two dogs are pulling at the same shoe, but
the show stays in place. What is
happening?
1. One dog is pulling with greater force.
2. Both dogs are pulling with the same
force.
3. Both dogs are pulling the shoe in the
same direction.
When workers spread sand over icy bridges and roads
in the winter, how does this help people drive on the
roads?
1. The sand increases friction between the road and
tires of the car.
2. The sand increases inertia of the car.
3. The sand increases the speed of the car.
4. The sand increases the momentum of the car.
1. Determine the total net force being placed on the
rope.
2. Which way will the rope be pulled? Support your
answer.