Physics 12/9 Classwork & Homework
Due for 12/11
Projectile Motion
First some terminology to remember:
 A student throws a baseball to a friend. As the ball moves
through the air it is called a projectile.
 The trajectory of a projectile launched at an angle is a
curve called a parabola.
 An object’s trajectory is its path through space.
 The time a projectile is in the air is the flight time.
Questions
1. Lucy and her friend are working at an assembly plant
making wooden toy giraffes. At the end of the line, the giraffes
go horizontally off the edge of a conveyor belt and fall into a
box below. If the box is 0.60 m below the level of the conveyor
belt and 0.40 m away from it, what must be the horizontal
velocity of giraffes as they leave the conveyor belt?
Hint: Use the example of horizontal launched projectiles for
this question.
2. A machine launches a tennis ball with an initial velocity of 28
m/s at 30 degrees to the horizontal.
a) What is the horizontal component of the velocity of the
ball (i) initially, (ii) after 1 second, (iii) after 2 seconds?
b) What is the vertical component of the velocity of the ball
(i) initially, (ii) after 1 second, (iii) after 2 seconds?
c) At what time will the ball reach its maximum height?
d) What is the maximum height reached by the ball?
e) What is the acceleration at the maximum height?
f) At which point in its flight experience its minimum
speed?
g) What is the minimum speed of the ball during its flight?
h) At what time does the minimum speed occur?
i) At what time after being launched will the ball return to
the ground?
j) What is the velocity of the ball as it strikes the ground?
k) Calculate the horizontal range of the ball.
Extra Practice Questions (Physics and Projectiles)
1. You throw a stone horizontally at a speed of 5.0
m/s from the top of a cliff that is 78.4m high.
(a) How long does it take the stone to reach the
bottom of the cliff?
(b) How far from the base of the cliff does the
stone hit the ground?
(c) What are the horizontal and vertical
components of the stone’s velocity just before
it hits the ground?
2. An arrow is shot at 30 degrees above the
horizontal. Its velocity is 49 m/s and it hits the
target.
(a) What is the maximum height the arrow will
attain?
(b) The target is at the height from which the
arrow was shot. How far away is it?