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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:
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- 9.9 m
- 10.1 m
- 10 m
- 20 m
Correct Option: B
No external force is acting, therefore, momentum is conserved.
By momentum conservation,
50 u + 0.5 × 2 = 0
where u is the velocity of man.
| u = - | ms-1 | |
| 50 |
Negative sign of u shows that man moves upward.
Time taken by the stone to reach the ground = 10/2 = 5s
Distance moved by the man 5 × (1/50) = 0.1 m
∴ when the stone reaches the floor, the distance of the man above floor = 10.1 m
