CBSE Class 9 Answered

(a) The rider falls in the forward direction when a running horse stops suddenly because of inertia of motion which is the tendency to be in state of motion and continue even when the horse stops suddenly.

(b) Mass is the measure of inertia. A cricket ball has larger mass than a tennis ball. Thus, it has larger inertia than the tennis ball. Therefore, the cricket ball needs a larger force to be stopped.

(c) If the athlete runs some distance before taking the jump, then inertia of motion helps the athlete to continue the state of motion which aids him to take a longer jump.