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11th grade Compare devices that change energy from one form to another worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

Level: Building Confidence · On Level · Challenge Me

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Compare devices that change energy from one form to another

Grade 11 Science Worksheet - Building Confidence

NameDate

Circle the best answer, or write your answer on the line.

  1. Bo's motor takes 300 W and lifts a 50 kg load 2 m in 5 s. With g = 9.8 m/s², what is its efficiency in percent?

  2. Esme's motor takes 200 W and lifts a 12 kg load 5 m in 4 s. With g = 9.8 m/s², what is its efficiency in percent?

  3. A fan takes in 800 J. It gives out 40 J of sound and 520 J of thermal energy; the rest is moving air. What are the useful energy and efficiency, Jun?

    • 280 J useful, 35% efficient
    • 240 J useful, 3.3% efficient
    • 560 J useful, 70% efficient
    • 240 J useful, 30% efficient

  4. Which energy chart in the table cannot be right, Luz?

    • No chart is wrong: any may lose some energy for good
    • Z: more than half of its energy is wasted
    • Y: its outputs add to 350 J, more than the 300 J in
    • X: its outputs exactly match its input

  5. Which list gives the energy forms in order in a coal power plant, Milo?

    • Chemical, thermal, kinetic, electrical
    • Chemical, thermal, electrical, kinetic
    • Thermal, chemical, kinetic, electrical
    • Chemical, kinetic, thermal, electrical

  6. Which list gives the energy forms in order in a hydroelectric dam, Noah?

    • Gravitational, kinetic, electrical
    • Kinetic, gravitational, electrical
    • Gravitational, electrical, kinetic
    • Chemical, kinetic, electrical

  7. An electric car slows by regenerative braking. Which list gives the energy forms in order, Pia?

    • Kinetic, electrical, chemical (battery)
    • Kinetic, electrical, thermal in the brake pads
    • Chemical, electrical, kinetic in the wheels
    • Kinetic, thermal, chemical in the battery

  8. A phone charger feels warm while it charges. Where does that thermal energy come from, Ren?

    • The battery makes new thermal energy out of nothing
    • The charger destroys part of the electrical energy put in
    • Some input electrical energy becomes thermal energy
    • The warmth is sound energy that has changed form

  9. A lamp takes in 100 J and gives out 12 J of light. What happens to the other 88 J, Tala?

    • It spreads out as thermal energy in the room
    • It turns into light that our eyes cannot see
    • It goes back along the wire into the wall socket
    • It is used up in the lamp and disappears

  10. An inventor says a motor is 110% efficient. What is wrong with the claim, Zee?

    • Nothing is wrong, if the motor is well oiled
    • The percent alone is wrong: it should read 11%
    • Useful output cannot exceed the energy put in
    • Nothing is wrong, if the motor also stores energy
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11th grade Compare devices that change energy from one form to another worksheet – printable
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About this worksheet

Compare devices that change energy from one form to another. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find efficiency from powers (useful power m g h ÷ t over input power), and complete an energy balance from bars.
  • I can multiply efficiencies along a chain and work backwards from a target output, and find range, input power and kettle times with efficiency.
  • I can compare designs against constraints and goals (mass, cost, output per dollar), and know the Carnot limit 1 − Tc ÷ Th.
  • I can judge claims (a 100%-efficient heater, a round-trip battery rating, ten points at 40% against ten points at 80%) and design a test that finds where energy is lost.

Standard: HS-PS3-3

Words to know

efficiency: Useful energy out ÷ energy in, as a percent

useful output: The energy in the form the device is for

energy balance: Energy in = useful out + wasted out

criterion / constraint: A goal to do well on / a limit not to break

percentage point: One percent of the whole, as in 40% to 50% = 10 points

Common mistakes

Your child left out g when finding the useful power. Lifting a mass needs m g h, with g = 9.8 m/s².

Your child divided the input by the useful output. Efficiency is useful out over in, so it stays below 100%.

Your child used only the first efficiency. Every stage in a chain loses some energy.

Questions parents ask

What is the most common mistake with compare devices that change energy from one form to another?

Your child left out g when finding the useful power. Lifting a mass needs m g h, with g = 9.8 m/s².

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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