When does a ball bounce off the ground, which of the following changes suddenly? (Assume no loss of energy to the floor)

When a ball bounces off the ground, its momentum changes suddenly. Momentum is a vector quantity defined by the product of mass and velocity. Upon impact, the direction of the ball's motion reverses, causing a significant change in velocity and thus a sudden change in momentum. The question assumes no loss of energy, implying a perfectly elastic collision. In such a collision, kinetic energy is conserved before and after the impact. Since kinetic energy (1/2 mv²) depends on the square of speed, and the speed remains constant in an ideal elastic bounce, neither speed nor kinetic energy changes suddenly in magnitude. Potential energy depends on height and does not change abruptly at the moment of contact. Therefore, the sudden reversal of direction makes momentum the only property that changes instantaneously during the bounce.