# speed of the ball

1. From the top of a 75.0 m high building, a 1.00 kg ball is thrown directly downward with an initial speed of 8.00 m/s. If the ball reaches the ground with a speed of 32.0 m/s, the mechanical energy lost to friction is equal to:

a. 0 J

b. 255 J

c. 480 J

d. 735 J

e. 767 J

2. A 15-kg child stroller is moving towards you with a speed of 2.5m/s. How much work is required to stop the stroller?

a. 19 J

b. 38 J

c. 47 J

d. 94 J

e. 460 J

3. Joe throws a 0.15-kg rubble ball directly downward to the floor. The ball's speed just before impact is 6.5m/s and just after the impact is 3.5 m/s. If the ball is contact with the floor for 0.025 s, what is the magnitude of the average force that the floor exerts on the ball during the time of contact?

a. 3.0 N

b. 18 N

c. 30 N

d. 60 N

e. 130 N

https://brainmass.com/physics/system-work/determining-energy-work-magnitude-force-314124

#### Solution Summary

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