Motion (kinetic) energy, and how mass and speed change it
Grade 8 Science Worksheet
Circle the best answer, or write your answer on the line.
Ari and the bike have a mass of 50 kg and ride at 4 m/s. What is the motion energy?
Bo's 3 kg skateboard rolls across the park at 4 m/s. What is the motion energy?
Jun doubles the speed of a scooter, with the same rider. What happens to its motion energy?
- It becomes four times as much
- It doubles
- It halves
- It stays the same as it was before
Kira rolls a cart three times as fast as before. How does its motion energy change?
- Nine times as much
- Three times as much
- Six times as much
- The same
Luz slows a bike to half its speed. How does its motion energy change?
- It becomes double
- It becomes half
- It does not change
- It becomes one quarter
A wagon carries twice the load at the same speed. How does its motion energy change, Milo?
- Twice as much
- The same, since speed decides it
- Half as much
- Four times as much
Noah compares a 1 kg ball and a 3 kg ball rolling at the same speed. The 3 kg ball has…
- one third the motion energy
- three times the motion energy
- the same motion energy
- nine times the motion energy
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?
- Cart B, since mass counts double
- Cart B, since it is heavier
- Cart A
- The same, since 2 × 4 = 4 × 2
Ren's lab cart A bumps cart B. How much energy went to thermal energy and sound?
- 0 J; 3 J was used up
- 8 J
- 3 J
- 17 J
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.
Zee's toy ball knocks over plastic pins. How much motion energy did the pins get?
- 10 J
- 0 J; the hit used it up
- 5 J
- 6 J