A body of mass m is moving in a circle of radius r with a constant speed v. Th

Discussion Forum : Work Power And Energy

Question -

A body of mass m is moving in a circle of radius r with a constant speed v. The force on the body is $\frac{m v^{2}}{r}$ and is directed towards the centre. What is the work done by this force in moving the body over half the circumference of the circle

Options:

A .

\frac{m v^{2}}{π r^{2}}

B . Zero

C .

\frac{m v^{2}}{r^{2}}

D .

\frac{π r^{2}}{m v^{2}}

Answer: Option B
:
B

Work done by centripetal force is always zero, because force and instantaneous displacement are always perpendicular.

$W = \to F . \to s = F s c o s θ = F s c o s 90^{\circ} = 0$

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