Name: _____________________________________________ Block: ____________ Date: __________________
Mr. Almeida – Conceptual Physics
Free-Fall Worksheet
Δv = aΔt
Δs = v0Δt + ½ a(Δt)2
OR
OR
vf = vi + aΔt
s = si + v0Δ + ½ a(Δt)2
For all problems, suppose the acceleration due to gravity is -10 m/s2, with negative sign indicated a downward
direction. Neglect air resistance.
1. A tennis ball is dropped from a height of 100 m. Complete the table below regarding the ball’s speed.
t (s)
0
1.5
2.4
3.7
4.9
v (m/s)
0
15
24
37
49
2. While eating breakfast at the Eiffel Tower while on vacation, you drop your delicious morning croissant.
According to your tourist guide, the Eiffel Tower has a height of 300 m.
a. How many seconds does it take the croissant to hit someone out for their morning stroll?
Δt ≈ 7.7 s
b. How fast is it moving when it hits the passerby?
vf ≈ 77.5 m/s
3. A pebble dropped into a well hits the water in 2.3 seconds.
a. What is the depth of the well?
depth ≈ 26.5 m
b. If the speed of sound in air is 340 m/s, how much total time after you dropped the pebble would you hear
the sound?
time-to-rise ≈ 0.08 s
∴ total time ≈ 2.38 s
4. The empire state building is 381 meters tall.
a. If a penny is dropped from the highest point, how long would it take to make impact with the sidewalk?
Δt = 8.73 s
b. How fast would the penny be moving just before making impact?
vf = 87.3 m/s
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5. A rock is thrown vertically upwards at 30 m/s.
a. On the diagram to the right, label the velocity of the rock at each second.
b. Complete the table with information regarding the rock’s velocity.
t (s)
0
1
2
3
4
5
6
7
v (m/s)
30
20
10
0
-10
-20
-30
-40
c. Plot the velocity vs. time on the graph below.
6. If you throw a tennis ball upwards at 5.5 m/s, how long does it take to reach its apex (highest point)? How long
does it take to return to you?
Δt = 0.55 s
7. Jenny forgot her keys so Johnny throws them out the 3rd story window, which is 10 m above Jenny’s extended
hands.
a. How long does it take the keys to reach Jenny?
Δt = 1.4 s
b. How fast are the keys moving when they reach Jenny?
vf = 14 m/s
8. A wife, who owns an identical cell phone to that of her husband, mistakenly grabbed his on her way out this
morning. With what speed must she throw the cell phone up to her husband at the second floor window 3.6 m
above her so that it just reaches him? Why should she throw it at this speed as opposed to, say, a bit faster?
vi = 8.49 m/s
2
9. A rock is thrown with an initial speed of 20 m/s, with
the graph to the right describing its motion.
a. What is the acceleration of the rock?
a = -2 m/s
b. Is the rock being thrown on Earth?
Nope.
c. What is the speed of the rock when it reaches
its highest point?
vapex = 0 m/s
d. What is the displacement of the rock when it
reaches its highest point?
Δs = 100 m
10. On a hot summer day, a few LHS students decide to jump in a nearby lake. The step off the bridge and strike the
water 1.5 s later.
a. What is the height of the bridge?
Δ s = -11.25 m  height = 11.25 m
b. How fast are the swimmers moving when they strike the water?
vf = - 15 m/s … speed = 15 m/s
11. In a physics lab, a student dropping a watermelon off the roof of LHS times it to take 4.0 s to reach the ground.
When throwing the watermelon straight down, it strikes the ground in 3.0 s. What initial speed did she give the
watermelon?
vi = 11.67 m/s
3