Question

Determine the power involved if a 50kg student run 100 m in 11 second.

Answer 1

Given:

$m=50\:\rm kg$

$d=100\:\rm m$

$t=11\:\rm s$

The speed of the student

$$v=\frac{d}{t}=\frac{100\:\rm m}{11\:\rm s}=9.1\:\rm m/s$$

The power

$$P=\frac{E}{t}=\frac{mv^2/2}{t}\\=\frac{50\:\rm kg*(9.1\:\rm m/s)^2/2}{11\:\rm s}=188\:\rm W$$