A cyclist starts from the centre O of a circular park of radius one kilometre, reaches the edge P of the park, then cycles along the circumference and returns to the centre along QO as shown in the figure. If the round trip takes ten minutes, the net displacement and average speed of the cyclist (in metre and kilometre per hour) is
` `

Options

A. `0,1`
B. `(pi+4)/(2),0`
C. `21.4, (pi+4)/(2)`
D. `0,21.4`

Answer

D

Explanation

Net displacement of the cyclist = zero
Since the initial position coincide with the final position.
Average speed of the cyclist
`=("total distance travelled")/("total time taken")`
`=(OP+PQ+QO)/(10) km//min =(1+(pi)/(2)xx1+1)/(10)`
`=(pi+4)/(20)km//min=(pi+4)/(20)xx 60 km//hr`
`=21.4` km/hr.