Solution: Determine whether the sign of E is positive or negative for the system.a. A rolling billiard ball collides with another billiard ball. The first billiard ball (defined as the system) stops rolling aft

Determine whether the sign of E is positive or negative for the system.
a. A rolling billiard ball collides with another billiard ball. The first billiard ball (defined as the system) stops rolling after the collision.
b. A book falls to the floor. (The book is the system).
c. A father pushes his daughter on a swing. (The daughter and the swing are the system).