Energy, Work, and Power Flashcards

Water stored behind a dam is an example of which type of energy?

Answer: Gravitational potential energy

Water elevated behind a dam has gravitational potential energy due to its height above the turbines below.

A 60-watt light bulb runs for 2 hours. How much energy does it consume?

Answer: 120 watt-hours

Energy = Power × Time = 60 W × 2 h = 120 watt-hours.

In a pulley system, a worker pulls 6 feet of rope to raise a load 2 feet. What is the mechanical advantage?

Answer: 3

Mechanical advantage = effort distance / load distance = 6 / 2 = 3.

What happens to the potential energy of a roller coaster car as it descends a hill (ignoring friction)?

Answer: It converts to kinetic energy

As the car descends, gravitational potential energy converts to kinetic energy, increasing the car's speed.

Which of the following actions requires the most power?

Answer: Lifting 100 lbs 10 feet in 5 seconds

Power = Work/Time; 100×10/5 = 200 ft-lb/s is the highest among all choices.

A flywheel spins at high speed to store energy. This is an example of:

Answer: Rotational kinetic energy

A spinning flywheel stores rotational kinetic energy, which can be released to do work.

Which factor does NOT affect how much work is done when pushing a box across a floor?

Answer: The color of the box

Work = Force × Distance × cos(θ); the color of the box has no effect on work done.