Question

Which falling object will result in the least kinetic energy when it collides with the ground?(4 points)
Responses

100 grams of dirt falling at 15 m/s
100 grams of dirt falling at 15 m/s

100 grams of water falling at 10 m/s
100 grams of water falling at 10 m/s

10 grams of water falling at 1 m/s
10 grams of water falling at 1 m/s

10 grams of dirt falling at 2 m/s10 grams of dirt falling at 2 m/s

Answer 1

Use KE = 1/2 m v^2.

Compute each (m in kg):

- 100 g dirt, 15 m/s: KE = 0.5(0.100)(15^2) = 11.25 J
- 100 g water, 10 m/s: KE = 0.5(0.100)(10^2) = 5.00 J
- 10 g water, 1 m/s: KE = 0.5(0.010)(1^2) = 0.005 J
- 10 g dirt, 2 m/s: KE = 0.5(0.010)(2^2) = 0.02 J

Least kinetic energy: 10 grams of water falling at 1 m/s (0.005 J).