A cushioned bed or a sand bed is used in the athletic event high jump. Why?

Why does an athlete run before taking a high jump ?

Why does an athelete run before taking a high jump ?

Lubricant oil used in machines should be of high vescosity.Why?

An athlete runs a certain distance before taking a long jump . Why ?

Use Newton.s second law of motion to explain the following instances: You prefer to land on sand instead of hard floor while taking a high jump.

(a)In 'high jump' event the athletes are made to fall on a cushioned bed. Why? (b)What is the use of seat belts in cars?