# Unit 4, More About Forces Worksheet 7-

```Unit 4, More About Forces
Worksheet 7--Free Fall Problems
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Date__________________Period________
1.
A stone is thrown straight upward and it rises to a height of 20.0 m. With what speed was it thrown?
2.
A stone is thrown straight upward with a speed of 20.0 m/s. It is caught on its way down at a point 5.00
m above where it was thrown. What was its maximum height, how fast was it going when it was
caught, and how long did the trip take?
Answers: 20.4 m, 17.4 m/s, 3.80 s.
3.
A body falls freely from rest. Find a.) its acceleration, b.) the distance it falls in 3.00 s, c.) its speed
after falling 70.0 m, d.) the time required to reach a speed of 25.0 m/s, e.) the time taken to fall 300 m.
Answer: 9.81 m/s2, 44 m, 37.0 m/s, 2.55 s, 7.80 s
4.
A ball is dropped from rest at a height of 50.0 m above the ground. What is its speed just before it hits
the ground? How long does it take to reach the ground?
5.
A marble dropped from a bridge strikes the water in 5.00 s. Calculate the speed with which it strikes
and the height of the bridge. Answers: 49.0 m/s, 123 m.
6.
An antiaircraft shell is fired vertically upward with an initial velocity of 500 m/s. Neglecting friction,
compute a.) the maximum height it can reach, b.) the time taken to reach that height, c.) the
instantaneous velocity at the end of 60.0 s. d.) When will its height be 10.0 km?
Answers: 12.8 km, 51.0 s, 88.0 m/s downward, at t = 27.0 s and 75.0 s.
7.
A ballast bag is dropped from a balloon that is 300 m above the ground and rising at 13.0 m/s. For the
bag, find a.) the maximum height reached, b.) its position and velocity 5.00 s after being released, c.)
the time before it hits the ground.
Answers: 309 m, 242 m, 36.0 m/s downward, 9.30 s.
8.
A nut comes loose from a bolt on the bottom of an elevator as the elevator is moving up the shaft at 3
m/s. The nut strikes the bottom of the shaft in 2.00 s. a.) How far from the bottom of the shaft was the
elevator when the nut fell off? b.) How far above the bottom was the nut 0.250 s after it fell off?