Question

leslis observations
lesli observes what happens when she drops a rubber ball from a height of 1.0 meter onto a tile floor. she notices that the ball upward after it hits the ground. she also notices that the ball continues bouncing but each time the ball bounces it does not go as the previous bounce. she draws a graph to model what she observes.
based on the graph model, which statement best describe the potential energy is the greatest and when the kinetic en greatest?
a. the potential energy is greatest just before the ball floor and bounces, and the kinetic energy is greatest before the ball is dropped.
b. the potential energy and the kinetic energy are grea just before the ball hits the floor and bounces.
c. the potential energy and the kinetic energy are grea just before the ball is dropped.
d. the potential energy is greatest just before the ball dropped, and the kinetic energy is greatest just befo ball hits the floor and bounces.

Explanation:

• Potential energy ($PE = mgh$, where $m$ is mass, $g$ is acceleration due to gravity, and $h$ is height) depends on height. Just before the ball is dropped ($h = 1.0\ m$ initially), the height is maximum (for the first - drop case, and in general, potential energy is maximum at the highest point of each bounce, but comparing the start - just before drop has the highest potential energy among all moments in the motion described).
• Kinetic energy ($KE=\frac{1}{2}mv^{2}$) depends on velocity. Just before the ball hits the floor (and bounces), the ball has been accelerating downwards (due to gravity) and has maximum velocity (converting potential energy to kinetic energy as it falls).

Answer:

d. The potential energy is greatest just before the ball is dropped, and the kinetic energy is greatest just before the ball hits the floor and bounces.