Question

A toy car weighing 0.4 kg is at the top of a 0.8-meter ramp. It rolls to the bottom, reaching a speed of 3.5 m/s. What best explains why its final kinetic energy is less than its starting potential energy?

(1 point)
Responses

The car's mass was not held constant.
The car's mass was not held constant.

The force of gravity became much weaker.
The force of gravity became much weaker.

Energy was converted to heat by friction.
Energy was converted to heat by friction.

The ramp's angle was much too steep.
The ramp's angle was much too steep.

Answer 1

Energy was converted to heat by friction.

Explanation: mgh = 0.4·9.8·0.8 ≈ 3.14 J, while KE = ½·0.4·(3.5)^2 ≈ 2.45 J. The missing ≈0.69 J was dissipated (e.g. friction and rolling resistance) as heat/sound.