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PS 4 Key Sunday, September 06, 2009 9:36 AM

Problem Set 4: Free Fall

1. If a flea can jump to a height of 0.640 m, what is its initial velocity as it leaves the ground? How long does it take the flea to jump that high?

2. A brick is dropped from the roof of a building. The brick strikes the ground in 4.90 s. (a) How tall is the building? (b) What is the brick’s velocity as it strikes the ground?

3. A rock is thrown straight up with an initial velocity of 8.00 m/s from the roof of a building, 12.0 m above the ground. For the motion from the roof to the ground, what are the magnitude and direction of (a) the average velocity of the rock? (b) the average acceleration of the rock?

AP Physics Page 1


4. An egg is thrown nearly vertically upward from a point near the cornice of a tall building. It just misses the cornice on the way down and passes a point 50.0 m below its starting point 7.00 s after it leaves the thrower’s hand. (a) What is the initial speed of the egg? (b) How high does it rise above its starting point? (c) What is the magnitude of its velocity at the highest point? (d) What is the egg’s acceleration at the highest point? (e) What is the egg’s velocity at t = 3.00 s?

5. You are on the roof of the science building, 46.0 m above the ground. Ms. Gifford, who is 1.80 m tall, is walking toward the building at a constant speed of 1.20 m/s. If you wish to drop an egg on Gifford’s head, where should Gifford be when you release the egg?

AP Physics Page 2


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