Chapter 9, Problem 34E

Identify each energy exchange as primarily heat or work and determine the sign of $△E$ (positive or negative) for the system

1. A rolling billiard ball collides with another billiard ball The first billiard ball (defined as the system) stops rolling after the collision
2. A book is dropped to the floor. (The book is the system.)
3. A father pushes his daughter on a swing. (The daughter and the swing are the system.)