Work and Energy Physics Final Exam

A

An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. When released, the arrow will have a kinetic energy of ___ Joules A. 50 B. More than 50 C. Less than 50

D

An object at rest may have ___ A. Speed B. Velocity C.Acceleration D. Energy E. All of these

C

During a construction project, a 2500 N object is lifted high above the ground. It is released and falls 10.0 meters and drives a post 0.100 m into the ground. The average impact force on the object is ___ Newtons A. 2500 B. 25000 C. 250,000 D.2,500,000

B

Luke Autbeloe stands on the edge of a roof throws a ball downward. it strikes the ground with 100 J of kinetic energy. Luke now throws another identical ball upward with the same initial speed, and this too falls to the ground. Neglecting air resistance, the second ball hits the ground with a kinetic energy of ___ J. A. Less than 100 B. 100 C. 200 D. More than 200 E. None of these

B

Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building in 20.0 seconds. What power was required in this task. A. 20W B. 50W C.100W D.1000W E.20000W

C

Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters? A. Lifting the 50 kg crate B. Lifting the 25 kg crate C. Both require the same amount of work

A

A 10- Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ___ Joules. A. 0.5 B. 1 C. 10 D. More than 10

E

A 1000-kg car is moving at 40.0 km/hr when the driver slams on the brakes and skids to a stop (with locked brakes) over a distance of 20.0 meters. How far will the car skid with locked brakes if it is traveling at 120 km/hr? A. 20.0 m B. 60.0 m C. 90.0 m D. 120. m E. 180. m

C- the amount of work done by a force is found from W=f*d*cos(theta)

A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in a auto service station. Lifting the more massive car requires ___ work. a. less b. the same c. twice as much d. four times as much e. more than 4 times as much

B

A 50- kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ___ meters. A. 5 B. 10 C. 50 D. 100

C

A 50.0 kg crate is lifted to a height of 2.0 meters in the same time as a 25.0 kg crate is lifted to a height of 4 meters. The rate at which energy is used (i.e., power) in raising the 50.0 kg crate is ___ as the rate at which energy is used to life the 25.0 kg crate. A. Twice as much B. Half as much C. the same

A

A ball is projected into the air with 100 J of kinetic energy. The kinetic energy is transformed into gravitational potential energy on the path towards the peak of its trajectory. When the ball returns to its original height, its kinetic energy is ___ Joules. Do you consider the effects of air resistance A. Less than 100 B. 100 C. More than 100 D. Not enough information given

A

A child lifts a box up from the floor. The child then carries the box with constant speed to the other side of the room and puts the box down. How much work does he do on the box while walking across the floor at a constant speed? A. Zero J B. More than 0 J C. More information needed to determine

D

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of ___, but different amounts of ___. Pick the two words which fill in the blanks in their respective order. A. Energy, work B. Power, work C. Work, energy D. Work, power

D

A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water. A. 10 B. 500 C. 510 D. 5000 E.more than 5000