Free Fall and Projectiles
1. What are the ‘hidden givens’
a. All projectiles
b. Ball is dropped
c. Ball is thrown horizontally
2. What is the ‘Go To’ formula if you have a projectile:
a. Ball is dropped from known height and want time to impact.
b. Have time and horizontal displacement and want X-velocity
c. Have initial y velocity and want to know velocity at some time later.
d. A ball is thrown upward any you want to know how high it will go.
3. If a ball is thrown vertically upward with a speed of 10 m/s from a 24.6m high building, what is
the velocity when it comes back to the top of the building? [-10 m/s, or 10 m/s downward]
4. If a ball is dropped from a 24.6 m high building, how long does it take for it to hit the ground?
[2.24s]
5. If a projectile is launched horizontally with a speed of 12.0 m/s from the top of a 24.6-meter high
building. Determine the horizontal displacement of the projectile. [26.88 m]
6. Roll a bowling ball off the edge of a table. As it falls, its horizontal component of velocity _.
a. decreases
b. remains constant
c. increases
7. At what point in its path is the horizontal component of the velocity (vx) of a projectile the
smallest?
a. The instant it is thrown.
b. Halfway to the top.
c. At the top.
e. It is the same throughout the path.
d. As it nears the top.
8. At what point in its path is the vertical component of the velocity (vy) of a projectile the smallest?
Largest?
a. The instant it is thrown.
b. Halfway to the top.
c. At the top.
d. As it nears the top.
e. It is the same throughout the path.
9. 10 m/s. Where is the vertical velocity
a. 0m/s?
b. +10 m/s
c. -10 m/s [top, initial, impact]
10. An object is undergoing free fall motion. As it falls, the object's ____.
a. speed increases
b. acceleration increases
c. both of these
d. none of these
11. Which of the following statements are true of the vertical motion of projectiles? List all that
apply.
a. The vertical component of a projectile's velocity is a constant value of 9.8 m/s.
b. The vertical component of a projectile's velocity is constant.
c. The vertical component of a projectile's velocity is changing.
d. The vertical component of a projectile's velocity is changing at a constant rate.
e. A projectile with an upward component of motion will have a upward component of
acceleration.
f. A projectile with an downward component of motion will have a downward component
of acceleration.
g. The magnitude of the vertical velocity of a projectile changes by 9.8 m/s each second.
h. The vertical velocity of a projectile is 0 m/s at the peak of its trajectory.
i. The vertical velocity of a projectile is unaffected by the horizontal velocity; these two
components of motion are independent of each other.
j. The final vertical velocity of a projectile is always equal to the initial vertical velocity.
k. The vertical acceleration of a projectile is 0 m/s/s when it is at the peak of its trajectory.
l. As a projectile rises towards the peak of its trajectory, the vertical acceleration will
decrease; as it falls from the peak of its trajectory, its vertical acceleration will decrease.
m. As a projectile rises towards the peak of its trajectory, the vertical acceleration is directed
upward; as it falls from the peak of its trajectory, its vertical acceleration is directed
downward.
n. The peak height to which a projectile rises above the launch location is dependent upon
the initial vertical velocity.
o. As a projectile rises towards the peak of its trajectory, the vertical velocity will decrease;
as it falls from the peak of its trajectory, its vertical velocity will decrease.
12. Which of the following statements are true of the horizontal motion of projectiles? List all that
apply.
a. A projectile does not have a horizontal velocity.
b. A projectile with a rightward component of motion will have a rightward component of
acceleration.
c. The horizontal velocity of a projectile changes by 9.8 m/s each second.
d. A projectile with a horizontal component of motion will have a constant horizontal
velocity.
e. The horizontal velocity of a projectile is 0 m/s at the peak of its trajectory.
f. The horizontal velocity of a projectile is unaffected by the vertical velocity; these two
components of motion are independent of each other.
g. The horizontal displacement of a projectile is dependent upon the time of flight and the
initial horizontal velocity.
h. The final horizontal velocity of a projectile is always equal to the initial horizontal
velocity.
i. As a projectile rises towards the peak of its trajectory, the horizontal velocity will
decrease; as it falls from the peak of its trajectory, its horizontal velocity will decrease.
13. Which of the following descriptions of moving objects accurately portray a projectile? List all
that apply.
a. an object which is moving through the air and not touching any surface
b. a falling skydiver with an open parachute
c. any object upon which air resistance is negligible
d. a free-falling object
e. an object upon which the only significant force is the force of gravity
f. a falling feather
g. a falling feather in a vacuum chamber
h. a falling feather in a falling vacuum chamber.
14. Which of the following statements are true of projectiles? List all that apply.
a. A projectile is a free-falling object.
b. A projectile experiences negligible or no air resistance unless stated.
c. A projectile must be moving in the downward direction.
d. A projectile must be accelerating in the downward direction.
e. A projectile does not have to have horizontal motion.
f. A projectile could begin its projectile motion with a downward velocity.
g. A projectile does not need to be "falling."