A 50-N force acts on a 2-kg crate that starts from rest. When the force has been acting for 2 s the rate at which it is doing work is:

Question

Quizplus · Accepted Answer

The work done by the force is equal to the force times the distance moved in the direction of the force. The acceleration of the crate is $ a = \frac{F}{m} = \frac{50 \, \text{N}}{2 \, \text{kg}} = 25 \, \text{m/s}^2 $. The velocity after 2 seconds is $ v = at = 25 \, \text{m/s}^2 \times 2 \, \text{s} = 50 \, \text{m/s} $. The power, or rate of doing work, is $ P = Fv = 50 \, \text{N} \times 50 \, \text{m/s} = 2500 \, \text{W} $.

A 50-N Force Acts on a 2-Kg Crate That Starts