Question

An ant completes its motion along a circle at time 5 s. How much time will it take for it to travel along the diameter and come back? Assume that the ant is moving at a constant speed.

• A. 1.59 s
• B. 6.36 s
• C. 3.18 s
• D. 5.26 s

Answer 1

The correct option is C 3.18 s

Let us take the radius of the circle to be r.
In first case, distance travelled = $2\pi r$
In the second case, distance travelled will be 4r.
As speed of ant is constant, time taken will be proportional to distance travelled.
$T=\left(\frac{4r}{2\pi r}\right)\times 5$
$=\left(\frac{2}{\pi }\right)\times 5$
$=3.18s$