An athlete completes one round of a circular track of radius $10\, m$ in $40\, sec$. The distance covered by him in $2 \,min$ $20 \,sec$ is ........ $m$
An athlete completes one round of a circular track of radius $10\, m$ in $40\, sec$. The distance covered by him in $2 \,min$ $20 \,sec$ is ........ $m$
$70$
$140$
$110$
$220$
An athlete completes one round of a circular track of radius $10\, m$ in $40\, sec$. The distance covered by him in $2 \,min$ $20 \,sec$ is ........ $m$
Time period $= 40 \,sec$
No. of revolution $ = \frac{{{\rm{Total time}}}}{{{\rm{Time period}}}}$ $ = \frac{{140\,\sec }}{{40\,\sec }} = 3.5\,Rev$.
So, distance $ = 3.5 \times 2\pi R = 3.5 \times 2\pi \times 10 = 220\,m$.