Motion (kinetic) energy, and how mass and speed change it
Grade 8 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
Ari's 4 kg skateboard rolls at 3 m/s. Use KE = ½ × m × v². What is its motion energy?
Bo's 8 kg wagon rolls at 3 m/s. Use KE = ½ × m × v². What is its motion energy?
Esme's 4 kg bowling ball rolls at 5 m/s. Use KE = ½ × m × v². What is its motion energy?
Kira rolls the same ball twice: at 1 m/s, then at 3 m/s. When does it have more motion energy?
- The same, since it is one ball
- At 3 m/s
- At 1 m/s, since it rolls longer
A bowling ball and a tennis ball roll at the same 4 m/s. Which has more motion energy, Luz?
- The bowling ball
- The tennis ball, since it bounces
- The same, since the speeds match
Milo's cart stops when its brake rubs the wheel. How much thermal energy is made?
- 40 J
- 0 J; the energy was used up
- 20 J; half was lost
Read this first
Use this
Energy bar chart (example data), one bar per energy store, height in J. Sliding: motion 90 J; thermal 0 J. Stopped on the snow: motion 0 J; thermal ?. A transfer arrow goes from motion to thermal, labeled friction with snow.
Pia's sled slides to a stop on flat snow. How much thermal energy is made?
- 90 J
- 45 J
- 0 J
Motion energy of a 2 kg cart (example data)
speed (m/s) motion energy (J) 1 1 2 4 3 9 Ren's table shows a 2 kg cart's motion energy. Each value is the speed times itself. What is it at 4 m/s?
- 12 J
- 16 J
- 8 J
Motion energy of a 1 kg ball (example data)
speed (m/s) motion energy (J) 2 2 4 8 Tala's table shows a ball at 2 m/s and 4 m/s. When the speed doubled, what happened to the energy?
- It doubled
- It became four times as much
- It stayed the same
Zee's cart has 9 J of motion energy at 3 m/s. Doubling the speed gives four times the energy. What at 6 m/s?
- 12 J
- 18 J
- 36 J