Chapter 2 Extra Review

1. An object starts from rest and accelerates at 2 1. An object starts from rest and accelerates at 2.5 m/s2 for 15 seconds. What is its final velocity?

v = v0 + at v = 0 + 2.5(15) v = 37.5 m/s

2. A car is moving east at 35 m/s 2. A car is moving east at 35 m/s. If it accelerates at 20 m/s2 for a period of 22 seconds, what is its final velocity?

v = v0 + at v = 35 + 20(22) v = 475 m/s east

3. A ball is dropped from the top of a building 3. A ball is dropped from the top of a building. How fast is the ball falling after 5 seconds?

v = v0 + gt v = 0 + 10(5) v = 50 m/s

4. How far does the object in question 1 move over the 15 second period?

x = v0 t + ½ at2 x = 0(15) + ½ 2.5(15)2 x = 281 m

5. What is the total displacement of the car in question 2?

x = v0 t + ½ at2 x = 35(22) + ½ 20(22)2 x = 5610 m east

6. The ball in question 3 hits the ground after 10 seconds 6. The ball in question 3 hits the ground after 10 seconds. How tall is the building?

y = v0 t + ½ gt2 y = 0(10) + ½ 10(10)2 y = 500 m

7. A bottle rocket is launched horizontally and accelerates at 21 m/s2 7. A bottle rocket is launched horizontally and accelerates at 21 m/s2. What is its velocity when it is 300 meters from its launch point?

v2 = v02 + 2ax v2 = 02 + 2(21)300 v2 = 12600 v = 112 m/s

8. A base jumper falls until he reaches a speed of 200 m/s 8. A base jumper falls until he reaches a speed of 200 m/s. How far must he fall to reach that speed?

v2 = v02 + 2gy 2002 = 02 + 2(10)y y = 2000 m

9. A rock is thrown upward at a velocity of 100 m/s 9. A rock is thrown upward at a velocity of 100 m/s. How high does the rock ascend?

v2 = v02 + 2gy 02 = 1002 + 2(-10)y y = 500 m

10. How long does it take the rock in question 9 to reach its peak height?

v = v0 + at 0 = 100 + (-10)t t = 10 s

11. How long is the rock in questions 9 and 10 in the air?

The amount of time it takes to fall from the peak is the same as the time to reach the peak, so: 10 s X 2 = 20 s.

12. A car is moving 200 m/s. The driver hits the brakes and the car slows to a stop in 5 seconds. What is the acceleration?

v = v0 + at 0 = 200 + a(5) a = -40 m/s2

13. How far does the car in question 12 travel while slowing to a stop?

x = v0 t + ½ at2 x = 200 (5) + ½ -40(5)2 x = 500 m

OR v2 = v02 + 2ax 02 = 2002 + 2(-40)x x = 500 m

14. A ball rolls down a ramp with uniform acceleration 14. A ball rolls down a ramp with uniform acceleration. It travels 20 meters in 4 seconds. What is the acceleration?

x = v0 t + ½ at2 20 = 0 (4) + ½ a(4)2 a = 2.5 m/s2

15. A dog accelerates from a 2 m/s stroll to a 20 m/s run in 2 seconds 15. A dog accelerates from a 2 m/s stroll to a 20 m/s run in 2 seconds. What is the acceleration?

v = v0 + at 20 = 2 + a(2) a = 9 m/s2

16. How far does the dog in question 15 travel during the acceleration?

x = v0 t + ½ at2 x = 2 (2) + ½ 9(2)2 x = 22 m

OR v2 = v02 + 2ax 202 = 22 + 2(9)x x = 22 m