Question

A man of 50 kg mass is standing in a gravity free space at a height of 10 m above the floor. He throws a stone of 0.5 kg mass downwards with a speed 2 m/s. When the stone reaches the floor, the distance of the man above the floor will be:
(a) 9.9 m (b) 10.1 m (c) 10 m (d) 20 m

Answer 1

Let's denote :

Mass of the man (M) = 50 kg

Mass of the stone (m) = 0.5 kg

Velocity of man (V) = to be determined

Velocity of stone (v) = 2 m/s

Thus, MV = mv

50 × V = 0.5 × 2

V = 0.02 m/s

Now , as per the question, the distance given is 10m.

The time taken by the stone to cover 10m with velocity 2 m/s is 10/2 = 5 secs

Now in that 5 seconds, the man moves to a distance = 5 × 0.02 = 0.1m

Thus, the man moves up to a total distance of (10+0.1) = 10.1 m

That's it!