1. Energy Conversion of Energy Forms of Energy Energy Work

2. Work The product of force and distance moved in the direction of the force W = F x d Units: Newton-meter, Nm –Equivalent to Joule, J

3. Work Example A force of 10N is applied to a box to move it 2m along the floor. What is the work done on the box? A bodybuilder, 1.6 m tall lifted a 30-kg mass from the ground up to his head. How much work did he do?

4. Which force does more work?

5. Energy The ability to do work Work ~ Energy Units: Nm, J May be: –Transferred –Stored –Transformed

6. Forms of Energy Kinetic Energy –Energy due to motion –Equation: E K = ½ mv 2 Potential Energy –Energy due to position –Equation: E P = mgh

7. Examples What is the kinetic energy of a 3-kilogram ball that is rolling at 2 meters per second? What is the potential energy of a 3 kilogram-ball that is 3m above the ground?

8. Forms of Energy Chemical Energy –Energy due to chemical reaction Nuclear Energy –Energy due to nuclear reaction

9. Forms of Energy Thermal Energy –Energy transferred due to difference in temperature Electrical Energy –Energy due to movement of charges

10. Forms of Energy Light Energy Sound Energy

11. Conversion of Energy

12. Is this right or wrong?

13. Conversion of Energy

14. Example 1 A box of mass of mass 3 kg is dropped from a height of 5m. Neglecting air resistance, calculate: –The potential energy of the box before it is dropped –The kinetic energy of the box just before it reaches the ground –The speed of the box just before it strikes the ground

15. Example 2 A ball of mass 60 g is thrown upwards with an initial speed of 30 m/s. If air resistance is negligible, calculate: –The initial kinetic energy of the ball –The initial potential energy of the ball –The potential energy of the ball when it reaches its greatest height –The greatest height reached by the ball