A long belt is moving horizontally with a speed of `5 km h^(-1)`. A child runs on this belt to and fro with a speed of `9 km//h` (w.r.t. bett) between his father and mother located `50 m` apart on the belt. For an observer on a stationalry plateform outsied, what is the
(a) speed of the chils runningin the derection of motion of the belt, (b) speed of thechaild runing opposite to thedirection of the belt, and (c ) time taken by the child in cases (a) and (b) ? Which of theanswers change, if motion is viewed by one of the parents ?gt

Explanation

Let us consider, left to right be the positive direction of x-axis.
Since parent and child are located on the same belt, the speed of child as observed by stationary observer in either direction will be `(5)/(2)" ms"^(-1)`
Time taken by child in case (i) and (ii) is `t=(50)/(5//2) =20 s`