**Practice Problems: Free Fall**

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1. (easy) A small ball is released from a window at t = 0. Assuming free-fall conditions, how far does it travel in 2.8 seconds? If the ball had more mass would it fall a greater distance?

2. A rock is dropped from a garage roof from rest. The roof is 6.0 m from the ground.

a. (easy) Determine how long it takes the rock to hit the ground.

b. (easy) Determine the velocity of the rock as it hits the ground.

c. (moderate) A second rock is projected straight upward from ground level at the moment the first rock was released. This second rock had an initial upward velocity of +6.0 m/s. How long will this second rock take to reach maximum height?

d. (hard) At what time after release will the two rocks have the same height?

3. (moderate) A projectile is shot upward at 189 m/s from a height of 20 m off the ground. How long will it take for the projectile to be at ground level?

4. (moderate) A hot-air balloon is hovering over a large public park. The operator of the balloon then makes the balloon begin to rise at a constant rate of 0.8 m/s. At some height from the ground the operator drops a rock from the basket. The rock takes 10.3 seconds to hit a target on the ground. How high (above the ground) was the rock when it was released and what was its maximum height?

5. (moderate) Design an experiment that would allow you to prove the following claim: "All objects accelerate toward the Earth at the same rate." Your answer should include a procedure (including a list of apparatus needed to perform the experiment) that a fellow student could follow to collect data and the calculations that could be made with that data to prove the claim.

6. (moderate) A model rocket enthusiast launches a rocket with a motion sensor in the launchpad. Assume y = 0 at the launchpad, that positive is up, and that the fuel mass is very small compared to the rocket body mass. Create qualitative y-t, v-t, and a-t graphs for an experiment that starts at lift off and ends when the rocket hits the Earth on the way back down. Assume free fall after the rocket fuel is used up.

7. (moderate) Determine the distance between two steel spheres (after 1.4 s) dropped from a tower if the second sphere was dropped 0.5 seconds after the first. Assume free-fall and that the spheres are dropped from rest.

8. (OPTIONAL hard) If a ball is tossed up (free-fall conditions) with an initial speed of 2.0 m/s does it spend more time in the top 0.1 m of the toss or the bottom 0.1 m of the toss?

**PA Homeschooler Students: Prior to moving to the next assignment in the workflow, you must work through the following scenarios in the AP Physics 1 Student Workbook. If you have mastered the concepts, you should find that the questions in the scenarios can be easily answered. If not please take advantage of the additional practice found in the companion text.**

Click here to download Student Workbook.

Scenarios 1J and 1K