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11th grade Power worksheet

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Power

Grade 11 Science Worksheet

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  1. A motor drags a 40 kg crate 6 m up a 30° ramp at steady speed in 8 s. Friction on the crate is 50 N. What power does the motor supply, Ari?

  2. A motor drags a 25 kg crate 4 m up a 30° ramp at steady speed in 5 s. Friction on the crate is 30 N. What power does the motor supply, Bo?

  3. A motor drags a 60 kg crate 5 m up a 30° ramp at steady speed in 10 s. Friction on the crate is 40 N. What power does the motor supply, Esme?

  4. A cyclist at a steady 5 m/s needs 200 W against air draw a line, which grows as the square of speed. What power is needed at a steady 10 m/s, Jun?

    • 1,600 W
    • 400 W
    • 800 W

  5. A motor supplies a steady 250 W as a cart climbs a slope. Its speed falls from 5 m/s to 2.5 m/s. What happens to the pull force, Kira?

    • It halves, from 50 N to 25 N
    • It stays at 50 N
    • It doubles, from 50 N to 100 N

  6. Water falling 20 m at 50 kg each second drives a turbine that keeps 80% of the energy. What electrical power does it deliver, Noah?

    • 12,250 W
    • 9,800 W
    • 7,840 W
    • 392 W

  7. Motor X draws 500 W and is 60% efficient. Motor Y draws 400 W and is 80% efficient. Which delivers more useful power, and by how much, Pia?

    • Motor Y, by 20 W
    • Motor X, by 20 W
    • Motor Y, by 100 W
    • Motor X, by 100 W

  8. A 1,200 kg car speeds up from rest to 20 m/s in 8 s. Ignoring draw a line, what is its average power, Ren?

    • 60 kW
    • 15 kW
    • 3 kW
    • 30 kW

  9. A 1,200 kg car gains speed at a steady 2.5 m/s². Ignoring draw a line, what power does the engine supply at the moment it reaches 20 m/s, Tala?

    • 30 kW
    • 480 kW
    • 60 kW
    • 24 kW

  10. A car speeds up from rest under a constant net force. Compared with its power at 8 s, how large is its power at 4 s, Zee?

    • A quarter as large
    • Half as large
    • The same, since the force is constant
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11th grade Power worksheet – printable
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About this worksheet

Power. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find power as work ÷ time, P = W ÷ t, in watts (1 W = 1 J/s), and move between W, kW, J, kJ, s, minutes and kWh.
  • I can find the power a machine draws from the power it delivers and its efficiency, and the power a lift needs on a slope with friction.
  • I can use P = Fv at a steady speed, and say how power grows when speed, load or height changes.
  • I can read power as the slope of a work-time graph and energy as the area under a power-time graph, and judge claims about power.

Standard: none (TX, FL)

Words to know

power: How fast work is done: joules each second

watt (W): One joule each second

kilowatt (kW): 1000 watts

steady speed: Speed that doesn't change, so no energy goes into speeding up

slope: Rise ÷ run on a graph; on a work-time graph, the power

efficiency: Share of the power a machine draws that becomes useful work

kilowatt-hour (kWh): Energy used by 1 kW running for 1 hour: 3.6 million J

area under a graph: On a power-time graph, the area is the energy delivered

Common mistakes

Your child used the useful power and skipped the efficiency. A machine that wastes energy must draw more power than it delivers.

Your child multiplied by the efficiency instead of dividing. A motor always draws more power than it delivers.

Your child counted only the lift up the slope. The motor also works against friction over the same distance.

Questions parents ask

What is the most common mistake with power?

Your child used the useful power and skipped the efficiency. A machine that wastes energy must draw more power than it delivers.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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