Energy in Mechanical and Fluid Sysems II 5.2

I. Gravitational Potential Energy A. PE g = mgh B. Gravitational potential energy = (mass)(gravitational acceleration)(height)

II. Elastic Potential Energy A. Elasticity—an object’s or material’s tendency to return to its original shape after being stretched. B. Equilibrium position—unstretched position C. Spring constant (k)—force per unit distance D. PE elastic = ½ kx 2 E. Elastic Potential Energy = ½ (spring constant)(spring displacement) 2

F. Simple Harmonic Motion—spring alternately converting potential and kinetic energies. G. Examples of Elastic Potential Energy 1. Compressed golf ball 2. Bow and stretched string 3. Bent pole of pole vaulter 4. Rubber band

III.Bernoulli’s Principle and Equation A. As the velocity of a fluid increases, the pressure in the fluid decreases. B. P 1 + ρgh 1 + ½ ρv 1 2 = P 2 + ρgh 2 + ½ ρv 2 2