Potential Energy and Energy Conservation Chapter 7 Potential Energy and Energy Conservation

Gravitational potential energy The path of the basketball can demonstrate many principles of potential and kinetic energy.

Athletes and the conservation of energy Refer to Figure 7.3. Notice how potential and kinetic energy interchange as the athlete jumps.

Athletes and energy II—Example 7.1 Refer to Figure 7.4 as you follow Example 7.1. Notice how velocity changes as forms of energy interchange.

Forces other than gravity doing work Refer to Problem-Solving Strategy 7.1. Follow the solution of Example 7.2.

Work and energy along a curved path Notice the same expression for gravitational potential energy is the same along either a curved or straight path.

Consider projectile motion using energetics Consider the speed of a projectile as it traverses its parabola in the absence of air resistance. Refer to Conceptual Example 7.3 and Figure 7.8.

What’s the speed in a vertical circle? Refer to Example 7.4 and Figure 7.9.

Speed in a vertical circle with friction Consider how things change when friction is introduced. Refer to Example 7.5 and Figure 7.10.

The energy of a crate on an inclined plane Refer to Example 7.6 and Figure 7.11. The force of friction does negative work decreasing the total mechanical energy.

Work and energy in the motion of a mass on a spring Notice the work done as the spring expands and contracts at right in Figure 7.13.

Work and energy in the motion of a mass on a spring II See the parabolic potential energy curve in Figure 7.14 below. Problem-Solving Strategy 7.2 requires that we follow gravitational potential energy, kinetic energy, and elastic band potential energy.

Motion with elastic potential energy—Example 7.7 Example 7.8 also examines elastic potential energy.

Bring together two potential energies and friction Example 7.9 considers the emergency stop system on an elevator.

Conservative forces The work by a conservative force like gravity does not depend on the path your hiking team chooses, only how high you climb.

Friction does depend on the path taken Consider Example 7.10 where the nonconservative frictional force changes with path.

Energy diagrams give us insight Figure 7.23 shows the situation and the resulting energy diagram. Information may be discerned about limits and zeros for the physical properties involved.

The potential energy curve for motion of a particle Refer the potential energy function and its corresponding components of force.