1. Ch. 5 - Energy I. Energy & Work (pp. 256-332)  Energy  Work  Conservation of Energy  Thermal Energy

2. Make a table in your notes Type of Energy DescriptionExamples

3. A. Energy Types ENERGY The ability to cause change. motion of electric charges PE held in bonds between atoms Energy of moment/ potential movement internal energy of particles Energy released b/c of changes in the nucleus (fission or fusion) MECHANICAL CHEMICAL NUCLEARTHERMALHEAT ELECTROMAGNETIC El’c and mag’c energy in the form of waves transfer of energy b/c of a difference in temp. RADIANT/LIGHT ELECTRICAL “visible;” emitted by moving charged particles SOUND Measured in joules (J) Mechanical wave through medium

4. A. Energy Potential Energy (PE = mgh)  stored energy  depends on position or configuration of an object Which boulder has greater gravitational PE? What other ways can an object store energy?

5. A. Energy Kinetic Energy (KE = ½ mv 2 )  energy in the form of motion  depends on mass and velocity 80 km/h 50 km/h 80 km/h 80 km/h truck 50 km/h motorcycle Which has the most KE? Which has the least KE?

6. A. Energy Problems Calculate the KE of a 40 kg girl running on a track at 15 m/s. Calculate the gravitational PE of a 50 kg boy at the top of the stadium (12.5 m).

7. B. Work Work  transfer of energy through motion  force exerted through a distance W = Fd Distance must be in direction of force! W:work (J) F:force (N) d:distance (m) 1 J = 1 N·m

8. B. Work Brett’s backpack weighs 30 N. How much work is done on the backpack when he lifts it 1.5 m from the floor to his back? GIVEN: F = 30 N d = 1.5 m W = ? WORK: W = F·d W = (30 N)(1.5 m) W = 45 J F W d

9. B. Work A dancer lifts a 40 kg ballerina 1.4 m in the air and walks forward 2.2 m. How much work is done on the ballerina during and after the lift? GIVEN: m = 40 kg d = 1.4 m - during d = 2.2 m - after W = ? WORK: W = F·dF = m·a F =(40kg)(9.8m/s 2 )=392 N W = (392 N)(1.4 m) W = 549 J during lift No work after lift. “d” is not in the direction of the force. F W d

10. C. Conservation of Energy Law of Conservation of Energy  Energy may change forms, but it cannot be created or destroyed under ordinary conditions. EX:  PE  KE  mechanical  thermal  chemical  thermal

11. C. Conservation of Energy PE  KE View pendulum animation.pendulum animationView roller coaster animation.roller coaster animation

12. C. Conservation of Energy Mechanical  Thermal View rolling ball animations.rolling ball animationsView skier animation.skier animation