Swapping height for speed

Science · Energy · ages 15-16

Name ______________________ Date ____________

A 0.2 kg ball sits 1.8 m up (g = 10 N/kg). What is its gravitational store in J?
Answer: ______________
What is the kinetic energy equation?
- Half m v squared
- m v
- m g h
Doubling the speed doubles the kinetic store.
Circle one: True False
A 5 kg box rises 2 m (g = 10 N/kg). What is its gain in gravitational store?
- 10 J
- 20 J
- 100 J
A 2 kg mass moves at 3 m/s. What is its kinetic store in J?
Answer: ______________
The 0.2 kg ball falls 1.8 m. Which statement describes the energy swap?
- KE + GPE disappears
- Loss in GPE = gain in KE
- Loss in KE = gain in GPE
A ball is thrown upward at 6 m/s. Which calculation finds its maximum rise height?
- Multiply 6 by the mass
- Equate m g h to the launch kinetic store
- Divide top speed by g twice
A 0.5 kg ball lands with 16 J of kinetic energy. What is its landing speed in m/s?
Answer: ______________

Answer key

For grown-ups. Fold this page away before handing over the rest.

3.6 · 0.2 times 10 times 1.8 = 3.6 J.
Half m v squared · Kinetic = half times mass times speed squared.
False · Speed is squared, so doubling the speed quadruples the store.
100 J · 5 times 10 times 2 = 100 J.
9 · Half times 2 times 3 squared = 9 J.
Loss in GPE = gain in KE · Falling trades height store for motion store, joule for joule.
Equate m g h to the launch kinetic store · Launching asks for rise height: set the height store equal to the launch motion store.
8 · Half times 0.5 times v squared = 16 gives v squared = 64, so v = 8.