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?
Esme kicks a 0.5 kg ball, and it rolls at 6 m/s. What is the motion energy?
Luz slows a bike to half its speed. How does its motion energy change?
- It becomes one quarter
- It becomes half
- It becomes double
- It does not change
A wagon carries twice the load at the same speed. How does its motion energy change, Milo?
- Twice as much
- Four times as much
- The same, since speed decides it
- Half 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
- the same motion energy
- three times the 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 A
- Cart B, since mass counts double
- Cart B, since it is heavier
- 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
- 3 J
- 17 J
- 8 J
Tala coasts a bike up a hill until it stops. What happened to the 800 J of motion energy?
- It stayed as motion energy
- It became stored energy from height
- It was used up by the hill
- It went into the air as wind
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
- 6 J
- 5 J