# Kinematics & Free Fall Problems

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Kinematics & Free Fall Problems -- DO NOT WRITE ON THIS SHEET!

All work should be done on your own sheet of paper. Some of the answers are provided so that you can check your work.

1. Define each of the following physical quantities in your own words. Indicate what units are used to measure each quantity in the SI system.

Displacement:

Velocity:

Acceleration:

2. A car travels 17 km due east, then does a U-turn, and travels 23 km due west.

a) What total distance has the car traveled?

b) What is the total displacement of the car?

c) If the entire trip took 2.0 hours, determine the average speed of the car. Give your answer in both km/hour, and m/s. (show conversion)

d) If the entire trip took 2.0 hours, determine the average velocity of the car. Give your answer in both km/h, and mph. (show conversion)

3. Write down each of the following formulas:

a) Constant speed motion

b) No ‘v’ formula

c) No ‘d’ formula

d) No ‘t’ formula

e) No ‘a’ formula

For each of the following problems be sure to: List known & unknown quantities, write the formula, box answer with 2-3 significant digits and correct units.

4. A car decelerates uniformly from 24 m/s to 18 m/s in 3.0 seconds. How far does it travel during this time? d=63 m

5. A car is initially traveling at 17 m/s when the driver steps down hard on the gas pedal resulting in an acceleration of 3.0 m/s2. How fast will the car be moving 4.0 seconds later? v=29 m/s

6. A car initially traveling at 24 m/s slams on the brakes and moves forward 196 m before coming to a complete halt. What was the magnitude of the car’s deceleration? a = 1.47 m/s2

7. A bike that is coasting down a steep hill increases its speed from 8.0 m/s to 14 m/s. The length of the hill is 55 meters. How much time passes during the descent? t=5 s

8. How long does it take a hiker to walk 7.0 miles if her average speed is 2.0 miles per hour? t=3.5 hr

9. If a car’s brakes can decelerate the car at a rate of 8.0 m/s2, what is the minimum stopping distance of a car that is initially traveling 20.0 m/s? d=25 m

10. Starting from rest a model rocket accelerates upwards at 24 m/s2. How long does it take to reach a height of 192 meters? t = 4.0 s

11. Starting from rest a model rocket accelerates upwards at 24 m/s2. How fast will it be moving after it has traveled 192 meters? v=96 m/s

12. Complete the tables below, then create displacement vs. time, and velocity vs. time graphs for the rocket in problems 10 & 11.

|Time (s) |Displacement (m) |

|0.0 | |

|1.0 | |

|2.0 | |

|3.0 | |

|4.0 | |

|5.0 | |

|Time (s) |Velocity (m/s) |

|0.0 | |

|1.0 | |

|2.0 | |

|3.0 | |

|4.0 | |

|5.0 | |

Free Fall Problems (Assume that the effects of air resistance can be ignored).

13. A ball is dropped over the edge of a building. How fast is the ball moving 2.0 seconds after being dropped? v=19.6 m/s

14. A rock is dropped from a bridge that is 28 meters above a river. How long does it take the rock to hit the water? t=2.39 s

15. A lacrosse ball that is thrown straight upwards reaches a maximum height of 4.5 meters. At what speed was it thrown? vo=9.39 m/s

16. A soccer player heads the ball and sends it flying vertically upwards at a speed of 12.0 m/s. How high above the players’ head does the ball travel? d=7.35 m

17. A snow ball is thrown upward at a speed of 27 m/s. How high (above the position from which it was thrown) is the snow ball 3.5 seconds later? Also, how fast is it moving at that time? In what direction? d=34.5m, v=7.3 m/s down

18. A mis-hit golf ball flies straight up in the air. Exactly 4.0 seconds later it lands right next to the tee. How high up did the golf ball go? d=19.6 m

19. A cliff diver on an alien planet dives off of a 32 meter tall cliff and lands in a sea of hydrochloric acid 1.20 seconds later. Assuming that the extra-terrestrial’s initial speed was zero, what is the free fall acceleration of this strange world? g=44.4 m/s2

20. Two people are standing on the edge of a building that is 42 meters high (back on earth!). One person throws a tennis ball straight downward at a speed of 16 m/s. At the same exact time, the other person throws a tennis ball straight upward at 16 m/s. How long after the first tennis ball lands will the second tennis ball arrive at the ground? t2-t1= (4.985 s) – (1.719 s) = 3.27 s

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