A force applied on a body of mass 4 kg for 5 seconds changes its velocity from10 m/s to 20 m/s. The power required is [[1]] W.

A force applied on a body of mass

4 kg

for

5

seconds changes its velocity from

10 m / s to 20 m / s

. The power required is

120 W .

Given:

m = 4 kg

t = 5 s

u = 10 m / s

v = 20 m / s

Using kinetic energy formula we have,

W = \frac{1}{2} m (v^{2} - u^{2})

\Rightarrow

= \frac{1}{2} m (20^{2} - 10^{2})

\Rightarrow = \frac{1}{2} \times 4 \times (400 - 100)

\Rightarrow

= \frac{1}{2} \times 4 \times 300

\Rightarrow W = 600 J

Power = \frac{W}{t}

\Rightarrow = \frac{600 J}{5 s}

\Rightarrow = 120 W

A force applied on a body of mass $4 kg$ for $5$ seconds changes its velocity from $10 m / s to 20 m / s$ . The power required is [[1]] $W$ .