On a long horizontally moving belt figure, a child runs to and fro with a speed 9 km h–1 (with respect to the belt) between his father and mother located 50 m apart on the moving belt. The belt moves with a speed of 4 km h–1. For an observer on a stationary platform outside, what is the

(a) speed of the child running in the direction of motion of the belt ?.

(b) speed of the child running opposite to the direction of motion of the belt?

(c) time taken by the child in (a) and (b)?

Which of the answers alter if motion is viewed by one of the parents?

Asked by Abhisek | 1 year ago |  207

##### Solution :-

Speed of child = 9 km h-1

Speed of belt = 4 km h-1

(a) When the boy runs in the direction of motion of the belt, then his speed as observed by

the stationary observer = (9 + 4) km h-1 = 13 km h-1.

(b) When the boy runs opposite to the direction of motion of the belt, then speed of child as

observed by the stationary observer = (9 – 4) km h-1 = 5 km h-1

(c) Distance between the two parents = 50 m = 0.05 km

Speed of the boy as observed by both the parents is 9 km h-1

Time taken by the boy to move towards one of the parents =0.05 km/9k h-1=0.0056 h =20 S

Answered by Pragya Singh | 1 year ago

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