Energy Review

Which graph best represents the relationship between the elongation of an ideal spring and the applied force?

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The elongation of the springs produced by force F depends

• directly on both F and k
• directly on F and inversely on k
• inversely on F and directly on k
• inversely on both F and k

If the time required for a student to swim 500 meters is doubled, the power developed by the student will be

• halved
• doubled
• quartered
• quadrupled

While riding a chairlift, a 55-kilogram skier is raised a vertical distance of 370 meters. What is the total change in the skier’s gravitational potential energy?

• 5.4 × 10^1 J
• 5.4 × 10^2 J
• 2.0 × 10^4 J
• 2.0 × 10^5 J

A motor has an output of 1,000 watts. When the motor is working at full capacity, how much time will it require to lift a 50-newton weight 100 meters?

• 5 s
• 10 s
• 50 s
• 100 s

A boy pushes his wagon at constant speed along a level sidewalk. The graph below represents the relationship between the horizontal force exerted by the boy and the distance the wagon moves. What is the total work done by the boy in pushing the wagon 4.0 meters?

• 5.0 J
• 7.5 J
• 120 J
• 180 J

A 1200-kilogram car is moving at 10. meters per second when a braking force of 3000. newtons is applied. How much time is required to bring the car to rest?

• 0.40 s
• 2.5 s
• 25 s
• 4.0 s

The table below shows the weight of four athletes (A, B, C, and D) and the time required for each athlete to run from the base of a hill to its top. Which athlete ran up the hill with the greatest average power?

• A
• B
• C
• D

Student A lifts a 50.-newton box from the floor to a height of 0.40 meter in 2.0 seconds. Student B lifts a 40.-newton box from the floor to a height of 0.50 meter in 1.0 second. Compared to student A, student B does

• the same work but develops more power
• the same work but develops less power
• more work but develops less power
• less work but develops more power

What is the maximum distance that a 60.-watt motor may vertically lift a 90.-newton weight in 7.5 seconds?

• 2.3 m
• 5.0 m
• 140 m
• 1100 m