Question

A particle is moving along a circle such that it completes one revolution in $40$ seconds. In $2$ minutes $20$ seconds, the ratio $\frac{\text{ displacement }}{\text{ distance }}$ is

• A. $0$
• B. $\frac{1}{7}$
• C. $\frac{2}{7}$
• D. $\frac{1}{11}$

Answer 1

Answer: (D)

$T=40s$
If $t=2$ minute 20 second
$=2\times 60+20$
$=140s$
So, it has completed $3\frac{1}{2}$ revolution.
Distance travelled $=3\times 2\pi R+\pi R$
$=7\pi R$
Displacement $=2R$
$\frac{\text{ IDisplacement| }}{\text{ Distance }}=\frac{2R}{7\pi R}$
$=\frac{2}{7\times \frac{22}{7}}=\frac{1}{11}$