A cyclist starts from the centre O of a circular park of radius 1km , reaches the edge P of the park , then cycles along the circumference and returns to the centre along QO as shown in figure . If the round trip takes 10 min. what is the (a) net displacement . (b) average velocity and (c) average speed of the cyclist ?

Explanation

(a) Net displacement =zero as initial and final position of the cyclist is same
(b) Average velocity `=("Net displacement")/("Total time taken")`=zero
(c) Total distance travelled `=OP+PQ+QO`
`=OP+1//4(2pir)+QO`
`=(1+1+(1)/(4)xx2xx(22)/(7)xx1)`km
`=(25)/(7)km`
Average speed `=("Total path length")/("Total time taken")`
`=(25//7)/(10//60)km h^(-1)`
`=21.43 km h^(-1)` .