Question

den pushes a desk 400 cm across the floor. he exerts a force of 10 n for 8 s to move the desk. what is his power output? (power: p = w/t)
1.25 w
5 w
40 w
500 w

Explanation:

Step1: Convert distance to SI unit

The distance $d = 400\ cm=4\ m$.

Step2: Calculate work done

Work $W = F\times d$, where $F = 10\ N$ and $d = 4\ m$. So $W=10\ N\times4\ m = 40\ J$.

Step3: Calculate power

Power $P=\frac{W}{t}$, with $W = 40\ J$ and $t = 8\ s$. So $P=\frac{40\ J}{8\ s}=5\ W$.

Answer:

B. 5 W