In the question number 97, time taken by the child to go from father to mother and back to father is

Options

A. 10 s
B. 20 s
C. 30 s
D. 40 s

Answer

D

Explanation

Distance between the parents = 50 m
Since the parents and child are located on the same belt, the speed of the child as observed by the stationary observer in either direction (either from mother to father or from father to mother) will be `9 km h^(-1)(= 5/2 m s^(-1))`.
`therfore` Time taken by the child to go father to mother and back to father is
`t = 50/(5/2) + 50/(5/2) = 20 s + 20 s = 40` s.