Final answer:
The change in velocity of a highly elastic ball after it strikes a wall depends on its initial and rebound velocities; for an example ball thrown at 3 m/s and rebounding at 2 m/s, the change is 5 m/s. Elastic and inelastic collisions differ in terms of energy conservation, but momentum is conserved in both cases.
Step-by-step explanation:
When considering the change in velocity of a highly elastic ball after colliding with a wall, we can use the principles of conservation of momentum and elasticity. For example, if a tennis ball is thrown horizontally towards a wall at an initial velocity of 3 m/s and rebounds at 2 m/s, the change in velocity would be the final velocity subtracted from the initial velocity, considering the direction. In this case, the ball's velocity changes by 5 m/s (3 m/s - (-2 m/s)).
Similarly, when a ball bounces off a wall and changes its motion from 60° above the +x-direction to 60° above the -x-direction and retains its speed, the impulse delivered by the wall can be calculated using the formula for impulse, which is the change in momentum of the ball. It is important to note that when the collision is not perfectly elastic, as in the case of a tennis ball striking a wall with an initial speed of 15 m/s and rebounding with 14 m/s, the kinetic energy isn't conserved, although momentum is conserved.