A cyclist starts from the center O of a circular park of radius 1km, reaches the edge P of the park, then cycles along the PQ circumference and returns to the center along OQ as shown in fig. If the round trip taken ten minute, the (a) net displacement, (b) average velocity and (c) average speed of the cyclists (in kilometer and kinetic per hour) is

Explanation

a) Since both the initial and final positions are the same therefore the net displacement is zero.
b) Average velocity is the ratio of net displacement and total time taken. Since the net displacement is zero therefore the average velocity is also zero.
c) Average speed = `("distance covered")/("time taken")`
`=(OP + "Actual distance PQ + OQ)/(10"minutes")`
`(1km +1/4 xx 2pi xx 1km +1km)/(10//60h)`
`6(2+22/14)kmh^(-1)` = `6 xx 50/14km h^(-1)`
`=21.43 kmh^(-1)`