$A$ javelin throw is marked foul if an athlete crosses over the line marked for throw. Explain why the athletes often fail to stop themselves before the line.

(N/A) This occurs due to the $inertia$ of motion. An athlete runs for a considerable distance to build up momentum,which helps in throwing the javelin a longer distance. However,the large momentum of the athlete makes it difficult to stop abruptly before the marked line,and as a result,the athlete may cross the line,causing the throw to be declared foul.