Elastic Potential Energy Questions Elastic Potential Energy Elastic

Elastic Potential Energy • • • Questions <? > Elastic Potential Energy Elastic Examples Elastic + Gravitational Examples Non-conservative forces and friction

Elastic Forces •

Work done by relaxing spring •

2 types of Potential Energy • • KE+PE +PE KE+PE + PE

Elastic Example •

Elastic & Gravitational Example I •

Elastic & Gravitational Example I •

Potential Energy Zero Point • For gravitational PE – Arbitrary, anywhere you like. • For elastic PE – Must be at equilibrium! • For gravitational + elastic PE – Easiest to chose at elastic equilibrium for both – Gravitational (+) above (-) below

Elastic & Gravitational Example II •

Bungee Jump (cont) •

Elastic & Gravitational Example III •

Trampoline (cont) •

Forces and Work • Gravity (Potential Energy) • Elastic (Potential Energy) • Electrostatic (Potential Energy – next semester) • Molecular/ Nuclear (Potential Energy – take more physics) • Any other force whose work only depends on endpoints • Normal (Never does work) • Circular(Never does work) • Friction (Requires fudge factor) • Applied Forces (Requires fudge factor, or may not be appropriate for work/energy)

Additional Examples

Example I • Hanging vine • Only forces acting are gravity and tension in vine

Example II • Skier Only forces acting are gravity and normal force

Example III • Sled Only forces acting are gravity and normal force Since you know height, incline doesn’t matter (for frictionless)

Example IV • Only forces acting are gravity and spring (both PE’s)