Question

An 8 kg box is at rest and is pushed for 10 m with a 60 N force. If it's accelerated to 10 m/s, calculate the efficiency of the force.

Answer 1

2/3

Explanation:

The work done on the box is ...

Fd = (60 N)(10 m) = 600 N·m = 600 J

The amount of energy the box has as a result is ...

KE = 1/2mv² = (1/2)(8 kg)(10 m/s)² = 400 kg·m²/s² = 400 J

The ratio of box energy to energy input is ...

η = (400 J)/(600 J) = 2/3 . . . ≈ 66.7%