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8th grade Motion (kinetic) energy, and how mass and speed change it worksheet

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Motion (kinetic) energy, and how mass and speed change it

Grade 8 Science Worksheet

NameDate

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

  1. Bo's 3 kg skateboard rolls across the park at 4 m/s. What is the motion energy?

  2. Esme kicks a 0.5 kg ball, and it rolls at 6 m/s. What is the motion energy?

  3. Jun doubles the speed of a scooter, with the same rider. What happens to its motion energy?

    • It halves
    • It doubles
    • It stays the same as it was before
    • It becomes four times as much

  4. Kira rolls a cart three times as fast as before. How does its motion energy change?

    • Six times as much
    • The same
    • Three times as much
    • Nine times as much

  5. A wagon carries twice the load at the same speed. How does its motion energy change, Milo?

    • Four times as much
    • Twice as much
    • The same, since speed decides it
    • Half as much

  6. Noah compares a 1 kg ball and a 3 kg ball rolling at the same speed. The 3 kg ball has…

    • the same motion energy
    • one third the motion energy
    • three times the motion energy
    • nine times the motion energy

  7. Cart A is 2 kg moving at 4 m/s. Cart B is 4 kg moving at 2 m/s. Which has more motion energy, Pia?

    • The same, since 2 × 4 = 4 × 2
    • Cart B, since it is heavier
    • Cart A
    • Cart B, since mass counts double

  8. Ren's lab cart A bumps cart B. How much energy went to thermal energy and sound?

    • 3 J
    • 17 J
    • 0 J; 3 J was used up
    • 8 J

  9. Tala coasts a bike up a hill until it stops. What happened to the 800 J of motion energy?

    • It became stored energy from height
    • It stayed as motion energy
    • It was used up by the hill
    • It went into the air as wind

  10. Read this first

    Use this

    Energy bar chart (example data), one bar per energy store, height in J. Ball rolling: ball motion 10 J; pins motion 0 J; thermal and sound 0 J. After hitting the pins: ball motion 4 J; pins motion ?; thermal and sound 1 J. A transfer arrow goes from ball to pins, labeled the hit.

  11. Zee's toy ball knocks over plastic pins. How much motion energy did the pins get?

    • 0 J; the hit used it up
    • 10 J
    • 6 J
    • 5 J
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8th grade Motion (kinetic) energy, and how mass and speed change it worksheet – printable
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About this worksheet

Motion (kinetic) energy, and how mass and speed change it. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find motion energy with KE = ½ × m × v², with units.
  • I can predict: double the mass, double the energy; double the speed, four times the energy.
  • I can follow motion energy into other objects, stored energy and heat, with the total kept.

Standard: MS-PS3-1, MS-PS3-5

Words to know

kinetic (motion) energy: Energy an object has because it is moving

KE = ½ × m × v²: Half the mass times the speed times the speed

squared: A number times itself: 3² = 9

transfer: Energy moving from one object or store to another

thermal energy: Energy of particle motion; warming

Common mistakes

Your child left the ½ out of the motion-energy rule. Say it together: motion energy is one half times mass times speed squared.

Your child forgot to square the speed.

Your child thought doubling speed doubles motion energy. Make a table together: 1, 2, 3 m/s gives 1, 4, 9 times the energy.

What to say

Ask: what is the speed times itself? That number goes into the rule.

Questions parents ask

What is the most common mistake with motion (kinetic) energy, and how mass and speed change it?

Your child left the ½ out of the motion-energy rule. Say it together: motion energy is one half times mass times speed squared.

Are these 8th 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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