Physics – First Semester Review First Quarter Review Rev HW#1 1. A car is driven 125 km due west, then 65 km due south. What is the magnitude of the displacement? 2. What are the components of a vector of magnitude 1.5 m at an angle of 35° from the positive x-axis? 1.5 m 35°

3. Look at the distance vs time graph. a. What is the position of the object at t = 4 sec? b. What is the speed of the object at t = 2 sec, 4 sec, 6 sec? c. During which time interval(s) is the speed constant? 6 5 dist (m) 4 3 2 1 1 2 3 4 5 6 7 time (sec)

4. Look at the velocity vs time graph a. What is the velocity of the object at t = 3 sec? b. What is the accl of the object at t = 3 sec, 6 sec, 9 sec? c. What is the displacement of the object at t = 3 sec? 40 35 vel 30 (m/s) 25 20 15 10 5 1 2 3 4 5 6 7 8 9 10 time (sec)

5. If a car accelerates from rest at a constant 5.5 m/s2, how long will it need to reach a velocity of 28 m/s? 6. A race car is traveling at 44 m/s slows at a constant rate to a vel of 22 m/s over 11s. How far does it move during this time?

Rev HW#2 7. A car accelerates at a constant rate from 15 m/s to 25 m/s while it travels 125 m. How long does it take to achieve this speed? 8. A brick is dropped from a high scaffold. a. What is its velocity after 4.0 s? b. How far does the brick fall during this time? 9. On Earth, a scale shows that you weigh 585 N. a. What is you mass? b. What would the scale read on the moon (g = 1.60 m/s2)?

between the sidewalk and the metal sled runners? 10. A boy exerts a 36 N horizontal force as he pulls a 52 N sled across a cement sidewalk at constant speed. What is the coefficient of kinetic friction between the sidewalk and the metal sled runners? 11. What is the length of a pendulum with a period of 1.00 s? 12. What is the acceleration of this system? (Friction is negligible) .. 3kg 5kg

Rev HW#3 13. A stone thrown horizontally at a speed of 5.0 m/s from the top of a cliff 78.4m high. a. How long does it take the stone to reach the bottom of the cliff? b. How far from the base of the cliff does the stone hit the ground? 14. A runner moving at a speed of 8.8 m/s rounds a bend with a radius of 25 m. a. What is the centripetal acceleration of the runner? b. What agent exerts the force on the runner?

15. Tom has a mass of 70.0 kg and Sally has a mass of 50.0 kg. Tom and Sally are standing 20.0 m apart on the dance floor. Sally looks up and sees Tom. She feels an attraction. If the attraction is gravitational, find its size.

16. The driver of the 725 kg compact car suddenly applies the brakes hard of 2.0 s. As a result, an average force of 5.0 X 103 N is exerted on the car to slow it. a. What is the impulse acting on the car? b. What is the change in momentum of the car? c. If the final speed of the car was 0 m/s, what was the initial speed of the car?

Rev HW#4 17. Two freight cars, each with a mass of 3.0 X 105 kg, collide. One was initially moving at 2.2 m/s; the other was at rest. They stick together. What is their final speed? 18. A 0.50 kg cue ball is traveling at 2 m/s across a pool table when it collides with a stationary 0.4 kg 8-ball. After the collision, the cue ball is not moving. How fast is the 8-ball moving, if the collision was in a straight line?

19. A 0.50 kg ball traveling at 6.0 m/s collides head-on with a 1.00 kg ball moving in the opposite direction at a speed of 12.0 m/s. The 0.50 kg ball bounces backward at 14 m/s after the collision. Find the speed of the second ball after the collision.

20. A box that weighs 575 N is lifted a distance of 20.0 m straight up by a cable attached to a motor. The job is done is 10.0 s. What power is developed by the motor? 21. Stan raises a 1200-N piano a distance of 5.00 m using a set of pulleys. Stan pulls in 20.0 m of rope. a. How much effort force would Stan apply if this were an ideal machine? b. What is the ideal mechanical advantage?

Rev HW#5 22. A rifle can shoot a 4.20 g bullet at a speed of 965 m/s. Find the kinetic energy of the bullet as it leaves the rifle. 23. A 5 kg box is lifted to a table 0.8 m above the floor. What is the box’s change in potential energy?

24. A bike rider approaches a hill at a speed of 8.5 m/s. The mass of the bike and rider together is 85 kg. a. Find the initial kinetic energy of the system. b. The rider coasts up the hill. Assuming there is no friction, at what height will the bike come to rest? c. Does your answer to b depend on the mass of the system? Explain. 25. A 1 kg rock is dropped from a bridge 45 m above a river. At what speed does the rock hit the water?