Question

A body of mass 2 kg starts from rest and moves with uniform acceleration. It acquires a velocity 20$m{s}^{-1}$ in 4 s.
Find average power transferred to the body in first 2 s.

• A. 50 W
• B. 100 W
• C. 150 W
• D. 200 W

Answer 1

The correct option is A 50 W

$M=2kg$

$\Rightarrow u=0$ $v=20m/s$

$\Rightarrow a=\frac{v-u}{t}=\frac{20}{4}=5m/n^2$

at $2$sec

$\Rightarrow S=ut+\frac{1}{2}a{t}^2$ $S=\frac{1}{2}\times 5\times 4$

$=10m$

$\Rightarrow F=m\times a=2\times 5=10$

$\Rightarrow$ Average power $=\frac{F\times 9}{t}=\frac{10\times 10}{2}=50W.$

Hence, the answer is $50W.$