Question

A body of mass $10kg$ moves with a velocity $v$ of $2m/s$ along a circular path of radius $8m$. The power produced by the body will be

• A. 10 J/s
• B. 98 J/s
• C. 49 J/s
• D. zero

Answer 1

Answer: (D)

Power is defined as rate of change of energy in a system or the time rate of doing work.
$P=\frac{dE}{dt}$
$=\frac{dW}{dt}$
Also work $=$ force $\times$ displacement $=F\times d$
In a circular motion, displacement is zero, therefore,
$P=\frac{d}{dt}(F\times d)$
$=\frac{d}{dt}(0)=0$