Question

An object moving in a circular track of radius $7m$ completes one full revolution of the track in $7$ seconds. Its speed during the motion will be:

• A. $7m{s}^{-1}$
• B. $\pi m{s}^{-1}$
• C. $2\pi m{s}^{-1}$
• D. $14m{s}^{-1}$

Answer 1

The correct option is C $2\pi m{s}^{-1}$

Given: Radius of circular track $r=7m$, time taken to cover one circle $t=7seconds$
speed in case of uniform circular motion = $\frac{circumferenceofcircle}{time}=\frac{2\times \pi \times r}{t}$
speed$=\frac{2\times \pi \times 7}{7}=2\pi m{s}^{-1}$