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# 6 2012 ppt batfink energy review

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### 6 2012 ppt batfink energy review

1. 1. Focus during the entire Power Point activity. Solidify your studying skills during this class period. Perform your work in your science journal so you have created a study guide for the test. Call me over if you are having difficulty getting started. If your answer is confirmed as correct, become a student/teacher and help someone in class who does not understand the method used to solve the problem.
2. 2. Know Definitions of Key Terms & Symbols
3. 3. The Batallac, the 1500 kg car used by Batfink and Karate to fight crime, is stopped at a height of 35 meters at the top of a damaged bridge. You may assume there is no friction. How much energy has been transferred? What container is this energy stored in? Remember that Batfink is 50 kg and Karate is 150 kg.
4. 4. SOLUTION: How much energy has been transferred into which container? K U m = 1700 kg g = 9.8 m/s2 Δy = 35 m Ug Ug = 583,100 J F = -kΔl P = W/t
5. 5. What is the velocity of the Batallac just before it hits the water?
6. 6. SOLUTION: Final velocity. K U m = 1700 kg mb = 25 kg Δy = 35 m Ug = 583,100 J Vf Vf= 26.19 m/s F = -kΔl P = W/t
7. 7. Our heroes, Batfink and Karate, are stuck in quick drying cement. Big Ears Ernie has vertically displaced a one metric ton (1,000 kg) wrecking ball 4 meters and is attempting to smash them. How much energy is being stored in the g-field?
8. 8. SOLUTION: Find energy. K U m = 1000 kg Δy = 4 m g = 9.8 m/s2 Ug Ug= 39,200 J
9. 9. Draw an energy bar chart to illustrate the distribution of energy when the wrecking ball is displaced 3 meters at the opposite end of it’s swing.
10. 10. SOLUTION: Distribution of energy containers. K ET = 39,299 J m = 1000 kg Δy = 3 m g = 9.8 m/s2 U KE KE= 9,800 J
11. 11. 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 Total Energy Ug KE
12. 12. What was the force exerted on the wrecking ball to place it in its original position?
13. 13. SOLUTION: Find force. K U m = 1000 kg Δy = 4 m g = 9.8 m/s2 F F= 9,800 N
14. 14. The Batallac has come to a stop between the two bridge decks 81.87 meters above the icy river. What is the total energy in the gravitational field?
15. 15. SOLUTION: Find energy. K U m = 1700 kg Δy = 81.87 m g = 9.8 m/s2 Ug Ug= 1,363,954.2 J
16. 16. What is the maximum velocity the batallac will attain before hitting the water?
17. 17. SOLUTION: Find velocity. K U m = 1700 kg v Δy = 81.87 m g = 9.8 m/s2 Ug= 1,363,954.2 J v = 40.06 m/s
18. 18. How much time would it take for the batallac to reach the water below?
19. 19. SOLUTION: Find time. K U vi = 0 m/s vf = 40.06 m/s Δy = 81.87 m g = 9.8 m/s2 tf tf= 4.09 s
20. 20. Fortunately, Batfink is able to free himself from the Batallac and stop the car from falling into the river. How much force was needed to bring the car to a complete stop?
21. 21. SOLUTION: Find force. K U m = 1700 kg F Δy = -81.87 m g = 9.8 m/s2 Ug= 1,363,954.2 J F = -16,660 N
22. 22. If this force was applied during the entire fall of the Batallac, how much power did Batfink exert?
23. 23. SOLUTION: Find power. K U m = 1700 kg P Δy = 81.87 m g = 9.8 m/s2 Ug= 1,363,954.2 J Tf = 4.09 s P = 333,485.13 W
24. 24. Batfink is dropped through a trap door disguised as a welcome mat. If he falls 20 meters, what is his KE just before hitting the ground?
25. 25. SOLUTION: Find energy. K U m = 50 kg Δy = -20 m g = 9.8 m/s2 KE KE = -9,800 J
26. 26. Fortunately for Batfink, there was a spring on the floor under the trap door. If the force needed to compress this spring 3 meters is 2100 N, what is the spring constant?
27. 27. SOLUTION: Find spring constant. K U F = 2100 N Δl = 3 m k k = 700 N/m
28. 28. How far did the spring compress if all the energy from Batfink was transferred to the spring?
29. 29. SOLUTION: Find change in length. K U Us = 9,800 J k = 700 N/m Δl Δl = 5.29 m