PHYSICS

1. PHYSICS Gravitational Potential Energy

2. Work Done By The Force of Gravity s mg hO mg hf • Can do positive or negative work. • Example: Falling Basketball • mg is the only force acting on the basketball. • The initial height of the basketball is ho • The final height of the ball is hf • The displacement of the ball is s • To Calculate Work • W=(Fcos0)s with F = mg and 0 = 0° • Wgravity = mg(ho – hf)

3. Gravitational Potential Energy PE = mgh Units of GPE is joule (J) Work being done is equal to PE final – PE initial. Gravitational Potential Energy, like work and Kinetic Energy is scalar.

4. Conservative Vs Nonconservative Forces • Conservative Forces: • A force is conservative when the work it does on a moving object is independent of the path between the object’s initial and final positions. • A force is conservative when it does no net work on an object moving around a closed path, starting and finishing at the same point. • Work done by gravity depends only on the initial and final heights, and not the path between these heights.

5. Conservative Vs Nonconservative Forces • Nonconservative: • A forces is nonconservative if the work it does on an object moving between two points depends on the path of the motion between the two points.

6. Mechanical Energy An object can possess two kinds of energy: Kinetic energy and gravitational potential energy. The sum of KE and PE is called total mechanical energy. Wnc = (KEf-KEi) + (PEf – PEi)

7. Conservation of Mechanical Energy The total mechanical energy (E=KE + PE) of an object remains constant as the object moves, provided that the net wor done by external nonconservative forces is zero.

8. Total Mechanical Energy

9. Conservation of Mechanical Energy

10. Energy in Simple Harmonic Motion • LAB: • Energy in Simple Harmonic Motion • Preliminary Questions: • Write them out and then answer. • Procedure: • Describe what you did as detailed as possible. • Data: • Analysis Questions: • Write them out and then answer