Question

an athelets runs a certain distance before taking a long jump why ?

Answer 1

According to the Newton's law (o don't remember which one)
A body remains to be at rest or motion until an external force acts on it.
so while running, the body of an athlete is in motion, and while he jumps, his body continues to be in motion giving him a longer distance travelled in air.

Answer 2

Answer:

Reason: In order to attain a velocity that will aid them during the long jump.

Explanation:

[Concept Used: Inertia]

An athlete usually runs a certain distance before taking a long jump. The reason behind this lies in the fact that the certain distance covered gives them some velocity which may help do the long jump better.

Doing a jump requires a certain velocity additionally in order to complete the long jump successfully and cover a large distance after the jump. The higher is the velocity, chances are that higher will be the distance covered after the jump.

Therefore, athletes take a run-up before taking the jump.

Hope it helps ;-))