Answer:
a) (Positive), b) . The collision is not perfectly elastic.
Explanation:
a) The collision can be described by the Principle of Momentum Conservation and Principle of Energy Conservation:
The final velocity of the rock is:
b) The coefficient of restitution is the best criterion to distinguish elastic collsions from inelastic collisions, such criterion is the ratio of final energy of the system to initial energy of the system:
The collision is not perfectly elastic.
A. Decreasing negatively, velocity is constant
B. Object at rest, velocity is zero
C. Decreasing negatively, velocity is constant
D. Increasing positively, velocity is constant