1. Energy and Work Section 10.1 Physics

2. Objectives Describe the relationship btwn work and energy. Display an ability to calculate work done by a force. Identify the force that does work. Differentiate btwn work and power and correctly calculate power used.

3. Energy Energy: the ability of something to produce change in itself or the environment. Energy can come in many forms: –Thermal Energy. –Chemical Energy. –Potential Energy. –Kinetic Energy.

4. Energy Kinetic Energy: Energy of motion. To find kinetic energy mathematically, there is one main equation: –KE = ½ (m)(v²) –Kinetic energy equals one half mass times velocity squared.

5. Energy and Work Energy and work are related. Energy is used to do work. Work: The process of changing the energy of the system. Ex. Raking leaves. –System: you and raking leaves. –Chemical energy is changed into kinetic energy to rake the leaves.

6. Work W = Fd –Work equals force times distance. –The relationship between doing work and a resulting change in energy, W = ΔK. –Work-Energy Theorem: founded by James Prescott Joule. –Energy is measured in Joules: J.

7. Work Can work be done on an object such as a brick wall? No. The object on which the force is applied must move through a distance!

8. Practice Problems Page 227. 1-5.

9. Forces at an Angle W = Fd If a force is applied at an angle, the components need to be calculated. F x = F (cos Θ) F y = -F (sin Θ) Or to find the work: –W = Fd (cosΘ)

10. Practice Problems Page 229. 6-8.

11. Power and Work Power is the rate of doing work. P = W/t –Power equals work divided by time.

12. Practice Problems Page 231. 9-12.