Question

Two particles start moving from the same position on a circle of radius 20 cm with speed $40\pi$m/s and $36\pi$m/s respectively in the same direction. Find the time after which the particles will meet again.

Answer 1

Two particle start from the same position on a circle of radius$=20cm$

The speed $=40\pi m/s$

and $36\pi m/s$

Relative velocity of the first particle with respect to the slow one

$(40\pi -36\pi )m/s=4\pi m/s$

The circumference distance covered with this relative yer,

$4\pi =\frac{2\pi R}{T}$

(where $R=$ radius $T=$ time period)

$T=\frac{2\pi R}{4\pi }=\frac{1}{2}\times 20\times {10}^{-2}=\frac{10}{100}=\frac{1}{10}sec$

So, after $\frac{1}{10}$ sec they will again melt.