When we jump on a heap of sand, we don’t get hurt, but when we jump on a floor of concrete, we get hurt. Explain.
Hint: The feet dig deep into the sand in the event of a hop on the sand, so that the sand exerts less energy. Sand therefore only exercises less force on the feet, in line with the law of Newton.
Complete step by step solution: Whether a man is like a mound of sand on a soft landing, the man takes longer to avoid. The rate of dynamic transition is lower so a smaller force stops the guy and he is not injured. Sand therefore decreases the momentum of the man more softly, becoming gentle.
If the man lands like a cement floor on hard earth, his momentum, so little time, will be reduced to nothing. Due to which a strong opposite force can work on the individual, the rate of shift in momentum is great. This force will cause a man to be seriously wounded.
It takes a longer time for the person to touch the ground (or hard surface) as sand will compress. It slows the man's momentum gently due to longer time, and thus the man will either not get injured or can get less damage.
Note: When a person falls on concrete over sand, a person is likely injured and, as a person's body lands on sand, it tends to sink and therefore to relieve weight, but a concrete floor is tougher than water and is not dispersed as sand grains. The person is thus more wounded since the velocity of the falling body gets a very brief time on a concrete floor and is thus immediately brought into contact with the pavement. Whereas it doesn't happen to loose sand or dumbness and the sliding body takes longer to interpret the ground.