1. 3.2 Potential and Kinetic Energy Date, Section, Pages, etc. Mr. Richter

2. Agenda  Warm – Up  Review: What is Energy?  Notes:  What is Energy  Units of Energy  Potential Energy  Kinetic Energy  Tests Returned

3. Objectives: We Will Be Able To…  Define potential and kinetic energy.  Calculate potential and kinetic energy

4. Warm-Up:  Two objects of equal mass sit on two different window sills. One sits on a second floor window and one sits on a fifth floor window. Which object, if either, has more energy? Why?  On a separate sheet of paper, write your name, then 2-3 sentences explaining your thinking. You have 5 minutes.

5. Kinetic and Potential Energy

6. Energy  Review: Energy is a quantity that measures the ability to cause change.  Energy can cause changes  in motion: like position, speed, and momentum  in physical conditions: like temperature, or turning wood into ashes and smoke  Energy itself cannot be seen or felt, but we can see evidence of energy in other things.  Wind, rolling objects, batteries, gasoline, etc.

7. Units of Energy  In physics, energy is most commonly measured in Joules [J].  A Joule is a Newton-meter. [J = N-m]  A Joule is a measure of how much energy is required to push with 1 Newton of force for 1 meter.  Another unit of energy less commonly used in physics is the Calorie.  1 Calorie = 4187 Joules

8. Potential Energy  Potential energy is energy due to position. Objects in unstable positions have stored energy.  A stretched spring.  A weight on a window sill.  The most common form of potential energy is energy stored due to the height of an object: gravitational potential energy.

9. Calculating Potential Energy  Gravitational potential energy (E p ) depends on the mass of the object, and its height above the surface below.  What is the gravitational potential energy of a 10-kg object 5 meters above the ground?  4900 J

10. Kinetic Energy  Kinetic energy is energy due to an object’s motion. Moving objects also have the ability to cause change.  The energy of a moving object is equal to the amount of energy that would be needed to stop the object.

11. Calculating Kinetic Energy  The kinetic energy of an object depends of the mass of that object and its speed. It is closely related to (but not the same as) momentum.  What is the kinetic energy of a 50-kg skateboarder moving at 3 m/s?  225 J

12. Wrap-Up: Did we meet our objectives?  Define potential and kinetic energy.  Calculate potential and kinetic energy

13. Homework  p 69 Your Turn a and b  Science Fair  Notebook and Research due Wednesday  Rough draft of Procedure due Monday 12/3