A body of mass 1 kg starts from rest and moves with uniform acceleration. In 2 seconds, its velocity is $10…
A body of mass 1 kg starts from rest and moves with uniform acceleration. In 2 seconds, its velocity is $10 \mathrm{~m} / \mathrm{s}$. The power exerted on the body in one second is
20 W
25 W
50 W
100 W
Solution
$\begin{aligned} & P=\frac{W}{t} \\ & W=\text { change in } K E \\ \therefore \quad & W=\frac{1}{2} \mathrm{~m}\left(\mathrm{v}^2-\mathrm{u}^2\right)=\frac{1}{2} \times 1 \times 10^2=50 \mathrm{~J} \\ \therefore \quad & P=\frac{50}{2}=25 \mathrm{~W}\end{aligned}$