1. DAILY QUESTION January 28, 2009 1. What is potential energy?

2. Agenda1/28/09 Daily Question Chapter 12 Section 3 Notes Assignments: 1. Planning Stage of Roller Coaster Project

3. Energy Is the ability to do work Can be present when nothing is happening But, can only be observed when it is transferred from object to object SI unit for energy is: Joules (J)

4. Potential Energy (Energy of Position) The energy that an object has because of the position, shape, or condition of the object Elastic potential energy: energy stored in any type of stretched or compressed elastic material

5. Gravitational Potential Energy (GPE) Two objects separated by a distance contains GPE due to the gravitational attraction between the objects. Depends on: –Mass and Height If the height is the same, the larger apple has greater GPE If the mass is the same, the higher apple has greater GPE

6. Finding GPE Practice Problem: A car with a mass of 1200 kg at the top of a 42 m high hill, what is the GPE? GPE = mgh GPE = 1200 kg x 9.8 m/s 2 x 42 m GPE = 493920 J

7. Kinetic Energy (KE) The energy an object has because it is in motion Depends on: –Mass and Speed If you have 2 objects fall at the same speed, the one with more mass has more KE If you have 2 objects with the same mass, the one traveling at a faster speed has more KE

8. Finding KE Practice Problem: Calculate the KE of a 1500 kg car moving at 29 m/s. KE = (1/2)mv 2 KE = (1/2) x 1500 kg x (29 m/s) 2 KE = 630750 J

9. Roller Coaster Project Planning Phase 1.Read instructions on Worksheet 2.Read Pages 400 and 401 in textbook 3.Determine roles (recorder, spokeperson, constructor) record on Worksheet 4.Answer Planning Questions on Worksheet