Answer:
Let's analyze the situation using the principles of conservation of energy and momentum.
When the ball falls and hits the floor, its kinetic energy converts into potential energy at the highest point of the bounce. At this point, the velocity of the ball is momentarily zero, and all its initial kinetic energy is converted into potential energy.
Given that the ball rebounds elastically, it will have the same speed before and after the collision with the floor. Therefore, its velocity just before hitting the floor will be equal in magnitude but opposite in direction to its velocity just after leaving the floor.
Since the ball falls vertically downward and rebounds elastically, its velocity just before hitting the floor will be the same as its velocity just after leaving the floor, but in the opposite direction. Therefore, the correct answer is:
c) 5.0 m/s downward
