1. Warm Up List 3 forms of energy. List 3 forms of energy. List 3 ways energy can be transformed. List 3 ways energy can be transformed.

2. Energy Transformation When energy in an object goes from one form to another. - The energy of a pendulum bob goes from potential to kinetic and back again - A skydiver's energy goes from potential, to kinetic, to thermal - A car's energy goes from kinetic to thermal while braking

3. If A pendulum's bob has a mass of 0.2 kg. If it is released from a height of 0.3 m, what are: If A pendulum's bob has a mass of 0.2 kg. If it is released from a height of 0.3 m, what are: –A) Its total energy? –B) Kinetic energy at the bottom of its path? –C) Its velocity at the bottom of its path? –D)Its velocity at a height of 0.1 m?

4. A skydiver jumps from an airplane which is 5000 m above the surface of the earth, if his parachute deploys at 2000 m, what was his velocity just before the parachute is deployed? A skydiver jumps from an airplane which is 5000 m above the surface of the earth, if his parachute deploys at 2000 m, what was his velocity just before the parachute is deployed? Make a graph of his potential and kinetic energy, relative to his height. After deploying his parachute his velocity is a constant 10 m/s Make a graph of his potential and kinetic energy, relative to his height. After deploying his parachute his velocity is a constant 10 m/s

5. Terminal Velocity What does terminal velocity mean? What does terminal velocity mean? Do falling objects accelerate for the entire time that they are falling? Why or why not? Do falling objects accelerate for the entire time that they are falling? Why or why not? What does this mean in terms of energy? What does this mean in terms of energy?

6. Terminal Velocity – When the force of gravity downward on an object is equaled by the force of wind resistance upward, then a falling object falls at a constant velocity. Terminal Velocity – When the force of gravity downward on an object is equaled by the force of wind resistance upward, then a falling object falls at a constant velocity. –Depends on the mass, and surface area of the falling object –For humans it is about 120 mph or 54 m/s

7. How far (in physics land) would a person have to fall before they reach their terminal velocity? How far (in physics land) would a person have to fall before they reach their terminal velocity? In real life it is farther than this, why? In real life it is farther than this, why? Where does the energy go as a person's height (PE) decreases, without their velocity (KE) increasing? Where does the energy go as a person's height (PE) decreases, without their velocity (KE) increasing?

8. Thermodynamics Explains the transfer of heat energy. Explains the transfer of heat energy. –0th Law: If object A is in equilibrium with object B, and Object B is in equilibrium with object C, then A and C are also in equilibrium –1 st Law: the change in the internal energy of a closed system is equal to the sum of the amount of heat energy supplied to the system and the work done on the system

9. Thermodynamics 2 nd Law: Entropy (disorder) increases 2 nd Law: Entropy (disorder) increases 3 rd Law: If the temperature reaches absolute 0, entropy = 0. 3 rd Law: If the temperature reaches absolute 0, entropy = 0.

10. Engines There are physical reasons why we can't build a perfect engine. There are physical reasons why we can't build a perfect engine. Perfect Engine: Energy in = mechanical energy out. Perfect Engine: Energy in = mechanical energy out. Efficiency is the rating that tells us how good a given engine is at converting energy in, into energy out. Efficiency is the rating that tells us how good a given engine is at converting energy in, into energy out. –Automobile engines and refrigerators are very inefficient while heaters are relatively efficient

11. Electricity As a society we are very concerned with how we can convert mechanical energy (occurring naturally) and turn it into electrical energy. As a society we are very concerned with how we can convert mechanical energy (occurring naturally) and turn it into electrical energy.

12. Power Power = energy/time Power = energy/time –Appliances and lightbulbs are rated by the power they use –Electric bills come in terms of kWh

13. Forms of energy (power plants)‏ Nuclear (Fission or Fusion Nuclear (Fission or Fusion Solar Solar Wind Wind Coal Coal Oil Oil Hydroelectric Hydroelectric Geothermal Geothermal Tidal Tidal

14. In class Design a Rube Goldberg machine with 3 steps, explain how energy is transferred/transformed during and between each step. Design a Rube Goldberg machine with 3 steps, explain how energy is transferred/transformed during and between each step. Homework: none Homework: none

15. Homework Design a 5 step Rube Goldberg machine. Include labels and descriptions of where the energy goes (transfers) and how it is transformed at and between each step. Design a 5 step Rube Goldberg machine. Include labels and descriptions of where the energy goes (transfers) and how it is transformed at and between each step.