Energy and Power Quiz

Ten Energy and Power practice questions combine work, stored energy, power, efficiency, and cost calculations with concepts. Every answer is explained.

Free, with no sign-up.

For High school students and adults reviewing the topic.

About 14 minutes. 10 questions.

How does it work?

Choose one answer or enter a number in the stated unit, then check it.
Round only the final answer in a calculation.

What will you get?

Review a score and an explanation for every answer.

Question 1A constant force of 36 N acts along a displacement of 7 m. Find its work in J, rounded to one decimal place.

Enter a number in J.

Answers within 0.05 J of the expected value are accepted.

Question 2An object of mass 3 kg moves at 4 m/s at a height of 5 m above a chosen zero. Use g = 9.8 m/s². Find kinetic plus gravitational potential energy in J, rounded to one decimal place.

Enter a number in J.

Answers within 0.05 J of the expected value are accepted.

Question 3A motor transfers 1350 J in 9 s. Find its average power in W, rounded to one decimal place.

Enter a number in W.

Answers within 0.05 W of the expected value are accepted.

Question 4During operation, a machine receives 2400 J and delivers 780 J of useful output. Find its efficiency as a percentage, rounded to one decimal place.

Enter a number in %.

Answers within 0.05 % of the expected value are accepted.

Question 5Electricity costs $0.22 per kWh. A device draws 0.75 kW for 4 hours. Find the energy charge in dollars, rounded to two decimals. Ignore fixed charges.

Enter a number in dollars.

Answers within 0.005 dollars of the expected value are accepted.

Question 6Brakes slow a cart and warm the surroundings. Which account respects an isolated system containing both?

The motion store decreases while other stores increaseThe warm surroundings have created additional total energyThe vanished motion means that total energy has been destroyedThe final temperature replaces the need to account for transfers

Question 7A force supports a bag while it moves horizontally at fixed height. What work does that upward force do on the bag?

Positive work equal to force times horizontal distanceNegative work because gravity points toward the groundZero, since its direction is perpendicular to the displacementWork equal to the carrier’s total food energy use

Question 8Water samples have the same temperature but different masses. What follows about their thermal energy?

The larger sample has less energy because its heat is spread outMatching temperatures require identical quantities of matterThe heavier portion holds the greater total internal energyThe smaller sample must supply heat to the larger at equilibrium

Question 9An unused battery is described as storing a supply of electricity. Which correction fits its energy store?

The terminals contain a fixed number of watts waiting to escapeChemical arrangements provide the energy transferred by its circuitA battery stores power independently of any discharge durationLoose electrons inside the casing are the stored fuel

Question 10A spring is stretched well beyond the range where force rises proportionally with extension. How should its energy be found?

Keep the small-extension spring formula unchanged at any stretchUse the final force as the stored energy in joulesReplace the deformation with the mass of the springUse the measured force-displacement relation for that range

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