Question

Jumping on a cemented floor causes more injury than on a heap of sand.Give reason
URGENTTT

Answer 1

The sand particles have negligible bonding between them, so when you land on a sand surface the sand particles move downwards and increase the time of deceleration (from the velocity at which you hit the geound to absolute zero). As the time of declaration is increased,you experience a lower impulse.

Impluse=Force/Time

Force=the force at which you hit the ground. ie.your body weight x acceleration due to gravity(9.8m/s^2).

Time=the time period in which the body decelerates from its final velocity to an absolute zero.

Whereas in case of a concrete surface,the bonding between the particles is very strong and they barely move then you fall on them.This reduces the time of deceleration. As the time period reduces, you experience a higher Impluse .Thus you get more hurt when you jump on a concrete surface.

Answer 2

here ia your answer:-
when you jumps on sand sone of the energy is transfered to sand which pushes it away and rest comes back at us.
bt when we jump on a concrete floor there is same amount of reaction is produced when action is applied on floor hence it hurts more.

ACTION = -REACTION
action is equal and opposite to reaction.

hope it helped ^_^