1. PE, KE, AND TE DIAGRAMS AND HOW TO CALCULATE KINETIC ENERGY

2. Solving Energy Problems pg 299 (1-4) m = P E h = P E g*h g*m

3. kilohecto deka gram deci centi milli kghgdgg cgmg kilogramhectogramdekagramgramdecigramcentigrammilligram 1,0001001010.10.010.001 MASS

4. Answers to P E calculations (1.a) P E = 493,920J or… 4.9 x 10 5 J (1.b) P E = 5,605,600J or… 5.6 x 10 6 J (1.c) P E = 2802.8J or.. 2.8 x 10 3 J (2.) P E = 1.4 x 10 15 J (3.) h=14.84m (4.) m= 57.82kg

5. Calculating PE Which apple has more PE? Apples have a mass= 1.5kg Apple “ A ” height= 15m Apple “ B ” height= 20m Remember PE=mgh So… Apple “ A ” PE= 220.5J Apple “ B ” PE= 294 J So the winner is…Apple “ B ” Spectrum pg 698 (96-100) Apple “A” Apple “B” 15m 20m Mass of apples = 1.5kg

6. PE Calculations PE 1. PE= 6856.08J 2. m= 4.6 kg 3. h= 19.18m 4. PE=7763.8J 5. m=.348 kg 6. h= 24.7 m

7. Answers to P E calculations pg 698 (96-100) 96. PE= mgh(0.14kg)(9.8m/s 2 )(3.5m) PE=4.8J 97.h= PE/mg 6.6 J/ (74kg)(9.8m/s 2 ) h=.0091m 98. PE=mgh (67kg)(9.8m/s2)(2.04m) PE=1339.4J or 1.3x10 3 J 99. m= PE/gh88.9J/ (2.0m)(9.8m/s 2 ) m=4.5kg 100. h= PE/gm.744 J/ (.23kg)(9.8m/s 2 ) m=.33m

8. Total Energy Remember…Total Energy is all the energy in a system Remember the formula? TE=PE +KE+ Heat The heat in a system is the… FRICTION! Total Energy will equal the GPE at the highest point in system. Total Energy NEVER changes in a system! Because…what you put in is what you get out! Let ’ s see if it works…

9. Set up a Data Table PEKETE A= B= C= D= E=

10. Let ’ s Practice A E B C D Calculate the PE, KE and TE of the ball at the 5 positions. Assume there is no friction The mass of the ball is 8kg. Height = 200m Height = 0m Draw this picture and label it!

11. Set up a Data Table PE A= 15680J B= 11760J C= 7840J D= 3920J E= 0J TE A= 15680J B= 15680J C= 15680J D= 15680J E= 15680J KE A= 0J B= 3920J C= 7840J D= 11760J E= 15680J

12. Bungee Jumper Calculations Person ’ s mass = 2kg For A-E calculate on white boards: P E, K E, and T E (assume NO friction) Draw the picture and label it. Set up another data table!

13. P E, K E, and T E Calculations PE A.1960J B.1470J C.980J D.490J E.0J KE A.0J B. 490J C. 980J D. 1470J E. 1960J TE A. 1960J B.1960J C. 1960J D.1960J E. 1960J

14. 3. Two ice skaters, a man and a woman, are involved in a doubles skating competition. At one point both skaters are moving at the same speed next to one another. The man is twice as massive as the woman. Carefully read each of the following statements about the scenario and write down the statement you agree with. Explain your thinking. 1. Both skaters have the same KE since they are moving at the same speed. 2. The mass of the skaters is more important than the speed of the skaters in determining their KE. 3. Skater A has more KE since she is only half the mass of skater B. 4. Skater B has more KE since he is twice as massive as skater A 5. If Skater A doubles her speed, she will have the same KE as Skater B.

15. KINETIC Energy (K E ) Kinetic Energy (K E ) is the energy of any moving object. K E depends on the mass and the velocity (speed) of an object. Only ½ of the mass is used, but velocity is squared… so K E depends mostly on the velocity of the object. K E = ½m * v 2 Units are Joules!!! (J)

16. Speed vs. Velocity What ’ s speed? How fast an object is moving. Then what is velocity? Velocity is speed with direction! Ex. Traveling 90 m/hr north bound.

17. Solving KE Problems K E = ½ m * v 2 ***Remember PEMDAS (order of operations) 1 ST : Square the v 2 nd : Take half the mass 3 rd : Multiply 1/2m * v 2 Page 301 (1a. & 1b.)