Question

why a person falling on a cemented floor gets injured but a person falling on a heap of sand is not injured

Answer 1

this is because in heap of sand there is lot of space between the particles which on force reduces while cement is hard and solid which doesn't have much space between its particles. thus in the case of sand the impulse of force is less due to time duration of the activity being higher than in cement case. thus it hurts less in sand than cement!

hope this helps!

Answer 2

Solution:

When a person falling on a heap of sand  then the person is not injured because sand is not hard. There is large space between the particles of sand. Therefore, force acting  on the person during fall reduces but in case of cement , cement is hard and solid .There is no space between the particles .Therefore,  force acting  on the person during fall is large.

In sand case impulse force is less than the impulse force in cement case.

Hence, the person falling on a cemented floor gets injured but a person falling on a heap of sand is not injured