1. Work and Energy

2. Work Imagine: After a heavy snowstorm Ryan’s car gets stuck in the snow. He asks you to help him move it, and you agree to help. You shovel snow away from the car and try to push it backwards. Although you both try as hard as you can, the car will just not move. You and Ryan are both exhausted and decide to give up. Question: Did you do any work?????

3. Work NO!!!!!! In physics, work is only done when an object moves. Definition of work: when you put force on an object and the object moves.

4. Work One more thing… –In order for work to be done, the force has to be applied in the same direction that the object is moving Ex: picking up a box Pushing a table across the room If you just walk across the room with a heavy box, you are not doing any work!!!!

5. Examples of Work (Yes or No) Alex pushes against the wall and becomes exhausted Mia pushes her science book off the table Dennis carries a heavy tray full of food across the room A rocket lifting off into space Sarah pushes her car down the road because she ran out of gas

6. Work Remember, if you apply a force to an object, but the object doesn’t move, then no work has been done!!!!

7. Energy Whenever an object has the ability to do work, it is called energy (whenever a force moves an object, energy is present) Lots and lots of different kinds of energy BUT, ALL energy can be broken down in two categories

8. Kinetic Energy Kinetic Energy: energy when things are in motion Talk to your partner…. Any examples of kinetic energy???

9. Kinetic Energy Which do you think will have more kinetic energy? A. Throwing a bowling ball with a speed of 5 m/s B. Throwing a tennis ball with a speed of 5 m/s Kinetic energy will INCREASE as an object’s mass INCREASES

10. Kinetic Energy Which will have more kinetic energy? A.Throwing a tennis ball with a speed of 5 m/s B.Throwing a tennis ball with a speed of 10 m/s Kinetic energy will INCREASE as velocity INCREASES

11. Potential Energy Potential Energy: stored energy (energy of objects NOT in motion) Talk to your partner…. Any examples of potential energy???

12. Potential Energy Two types of potential energy: Elastic potential energy: the energy of objects that can be stretched or compressed (rubber bands) Gravitational Potential Energy: the energy of objects right before they fall

13. Potential Energy Which would have more energy? A.A huge bolder teetering on the edge of a cliff 100 meters off the ground B.A small rock teetering on the edge of a cliff 100 meters off the ground Potential energy INCREASES as mass INCREASES

14. Potential Energy Which would have more energy? A.A huge boulder teetering on the edge of a cliff 10 meters off the ground? B.A huge boulder teetering on the edge of a cliff 100 meters off the ground? Potential energy INCREASES as height INCREASES