DO NOW
A soccer ball which has a mass of 550 grams
is kicked at an acceleration of 40m/s2. What
is the force of the football?
A car has a mass of 150000g is sitting in a
parking lot on jupiter where acceleration due
to gravity is 25m/s2. What is the weight?
NOVEMBER 21, 2011
Do Now:
 WDYS/WDYT
 Pg. 184
Agenda:
 Do Now
 LO/SC
 2.5 Investigation (Model and
PhET)
 2.5 Physics Talk
 Learning Objective:
 Explain the shape of a projectile’s motion
and how it relates to the object’s range
 Compare horizontal motion to vertical
motion in projectile motion
 Success Criteria:
 Use mathematical models of free fall and
uniform speed to construct a physical
model of the trajectory of a projectile
 Use the motion of a real projectile to test
a physical model of projectile motion
 Use a physical model of projectile motion
to infer the effects of launch speed and
launch angle on the range of a projectile
INVESTIGATION 2.5
Tennis ball thrown
along wall at a model
What happens if we
change the angle?
Does the tennis ball
still follow the
trajectory?
SHOOTING A CANNON BALL
 phET
 http://phet.colorado.edu/en/sim
ulation/projectile-motion
 Write observations about how
the angle changes the vertical
and horizontal distance of the
cannon ball.
LAUNCHING A CANNON BALL
Angle
Range
Height
“Hang
Time”
15˚
30˚
45˚
60˚
75˚
Yes, you must really copy this in your journal
The shape of a projectile is a parabola. A 45
degree angle produces the maximum range
of a projectile. Objects launched at less
than 45 degrees have more horizontal
motion than vertical motion. Objects
launched at angles greater than 45 degrees
have more vertical motion and less
horizontal motion.
NOVEMBER 28
HW: 2.5 PTG #1-3, 6, 8, 9 DUE TUESDAY
Do Now:
 Explain why a 45º angle
produces the maximum
range of a projectile.
 Learning Objective:
 Explain the shape of a projectile’s motion
and how it relates to the object’s range
 Compare horizontal motion to vertical
motion in projectile motion
 Success Criteria:
Agenda:
 Do Now
 LO/SC
 2.5 Investigation (Model and
PhET)
 2.5 Physics Talk
 Use mathematical models of free fall and
uniform speed to construct a physical
model of the trajectory of a projectile
 Use the motion of a real projectile to test
a physical model of projectile motion
 Use a physical model of projectile motion
to infer the effects of launch speed and
launch angle on the range of a projectile
 http://www.youtube.com/watch
?v=T9lwrqdxaqE
PHYSICS TALK 2.5
What is a projectile?
 A fired, thrown, or otherwise
propelled object, such as a
bullet, having no capacity for
self-propulsion
How many motions
does a projectile have
and what are they?
 There are two kinds of motion
– vertical and horizontal.
 Example: horizontal speed of
launch penny and verical fall due to
gravity
PHYSICS TALK 2.5
 What is the shape of the path
of all trajectories?
 A parabola
PHYSICS TALK 2.5
What does the
trajectory look like
when you launch a
projectile from
different angles?
PHYSICS TALK 2.5
What observations
can be made about
the previous
diagram?
 All balls travel in parabolas
 The 45˚ launch angle
produces the greatest
range (largest distance)
 The distance traveled at
pair angles is identical (ex.
30˚ and 60˚, 20˚ and 70˚,
10˚ and 80˚)
 Small angles have greater
horizontal velocities but
are in the air a short time
 Large angles have smaller
horizontal velocities but
are in the air a long time.
PHYSICS TALK 2.5
What is being ignored
in all of the diagrams
that might make the
actual occurrence look
different?
 In sports, we often have
air resistance. This will
provide a force against
gravity that may cause a
projectile to stay in the
air longer than the
models show.
WHAT DO YOU THINK NOW?
Now that you have completed the
experiment and taken the notes, answer the
WDYTN questions on page 192 in your
journal.
HOMEWORK
HW: PTG pg 194 #1-9,
DO NOW
WDYTN Pg 192
QUESTIONS-USE GUTAU
A ball with a initial velocity of zero is dropped
from a rooftop above the ground. After 3seconds
the ball strikes the ground below the rooftop.
How fast is the ball traveling when it HITS the
ground?
How far will the ball have fallen in these 3
seconds?
A truck drives off a cliff with a initial velocity of 0
m/s. After 4 seconds the truck strikes the ground.
How fast is the truck traveling when it hits the
ground?
How far will the truck have fallen in these 4
seconds?