1. oneone SK-17B Objective: To apply formulas for energy in order to determine the amount of energy of an object Core Question: Can objects have both potential and kinetic energy at the same time? Drill: 1. Review your homework paper. 2. Do you have any energy questions?

2. oneone SK-17B Come up with an original example of kinetic energy and an original example of potential energy. Be prepared to support your ideas. Kinetic: Potential:

3. oneone SK-17B Pendulum Analysis When does a pendulum have the most kinetic energy? At the bottom of its swing When does a pendulum have the most potential energy? At the top of its swing

4. oneone SK-17B Video: http://www.youtube.com/watch?v=Jnj8mc04r9E

5. oneone SK-17B Formula Practice: Summary Notes

6. oneone SK-17B Ex. 1 - An object is traveling at a constant velocity of 8 m/s. It has a mass of 42 kg. What is its kinetic energy? kinetic energy = mass x velocity 2 2 kinetic energy = 42 kg x (8 m/s) 2 2 kinetic energy = 42 kg x 64 m 2 /s 2 2 kinetic energy = 2688 kg m 2 /s 2 2 kinetic energy = 1344 J

7. oneone SK-17B Ex. 2 – What is the weight in newtons of a 45 kg child? weight (newtons) = mass × gravitational acceleration weight (newtons) = 45 kg × 9.8 m/s 2 weight (newtons) = 441 N

8. oneone SK-17B Ex. 3 - An 8 N object is suspended at a height of 25 m. What is its potential energy? gravitational potential energy = weight x height gravitational potential energy = 8 N x 25 m gravitational potential energy = 200 N-m

9. oneone SK-17B Ex. 4 - A 4 kg object is suspended at a height of 5m. What is its potential energy? grav.potential energy = mass x grav. acceleration x height grav.potential energy = 4 kg x 9.8 m/s 2 x 5 m grav. potential energy = 39.2 kg m/s 2 x 5 m grav.potential energy = 196 J

10. oneone SK-17B Try This: A 25 kg object is falling through the air. At a height of 10 m it has a velocity of 85 m/s. Calculate both the kinetic and potential energy of the object. What is the object’s total energy?

11. oneone SK-17B KINETIC ENERGY kinetic energy = mass x velocity 2 2 kinetic energy = 25 kg x (85 m/s) 2 2 kinetic energy = 25 kg x 7225 m 2 /s 2 2 kinetic energy = 180,625 kg m 2 /s 2 2 kinetic energy = 90,312.5 J

12. oneone SK-17B Potential Energy grav.potential energy = mass x grav. acceleration x height grav.potential energy = 25 kg x 9.8 m/s 2 x 10 m grav. potential energy = 245 kg m/s 2 x 10 m grav.potential energy = 2450 J

13. oneone SK-17B TOTAL ENERGY TE = Kinetic Energy + Potential Energy TE = 90,312.5 J + 2450 J TE = 92,762.5 J

14. oneone SK-17B Homework: Energy Problems – Show all work using proper form.