1. Class Notes 4.19.11 Mechanical Energy and Work Equation Sheet HW: 3 sheets http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=345 Retake TEST by Thursday 4.21.11 Hw LATE -50% Twin Towers worksheet Late -40% Bouncing ball lab is due Thursday by 3pm. Staple all 3 packets together in order List for sports bus for Twins

2. Calculate the Potential energy from the drop height and the bounce height page 5 space 4 Always positive!

3. Use the average height for PE Describe ball #1m = ____ grams= ______kg (change heights to meters) Drop Height h D (m) Average Bounce Height h B (m) Drop PE D =mgh D (Joules) Bounce PE B =mgh B (Joules) Δ PE (PE B -PE D ) (Joules) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

4. What is energy slide

6. Mechanical Energy

7. The energy acquired by the objects upon which work is done is known as mechanical energy. Mechanical energy is the energy which is possessed by an object due to its motion or its stored energy of position. Mechanical energy can be either KE (energy of motion) or PE (stored energy of position).

8. An object which possesses mechanical energy is able to do work. In fact, mechanical energy is often defined as the ability to do work. Any object which possesses mechanical energy - whether it be in the form of PE or KE - is able to do work. That is, its mechanical energy enables that object to apply a force to another object in order to cause it to be displaced.

9. An object which possesses mechanical energy is able to do work. Gravity moved the mass down!! Notice how the spike moved faster

10. Energy transactions with the bouncing ball lab. If COR =1 The force squashed the ball!!

11. Energy transactions with the bouncing ball lab. If COR <1 The force squashed the ball!! And energy is lost to T.M.E.

12. Mechanical Energy Equations Always positive! Page 5 space 5

13. Mechanical Work Equations in any direction Page 5 space 6 Always positive!

14. Mechanical Work Equations Page 6 space 1 Moved vertically Always positive!

15. Mechanical Power Equations POWER –how fast work is done Page 6 space 2 Always positive!

16. Mechanical Power Equations POWER –how fast work is done Page 6 space 3 Always positive!

17. Work Time Labs due Thursday Try the worksheets you have. We will continue with this topic tomorrow. Lab on THURSDAY?? Possible Quiz Thursday on Equations