* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Name: Period: _____ Date
Dark energy wikipedia , lookup
Efficient energy use wikipedia , lookup
Open energy system models wikipedia , lookup
Energy subsidies wikipedia , lookup
Energy storage wikipedia , lookup
100% renewable energy wikipedia , lookup
Low-Income Home Energy Assistance Program wikipedia , lookup
Potential energy wikipedia , lookup
Zero-energy building wikipedia , lookup
Public schemes for energy efficient refurbishment wikipedia , lookup
Low-carbon economy wikipedia , lookup
World energy consumption wikipedia , lookup
Energy Charter Treaty wikipedia , lookup
Kinetic energy wikipedia , lookup
Alternative energy wikipedia , lookup
Energy policy of Australia wikipedia , lookup
International Energy Agency wikipedia , lookup
Energy returned on energy invested wikipedia , lookup
Internal energy wikipedia , lookup
Energy policy of the United Kingdom wikipedia , lookup
Regenerative brake wikipedia , lookup
Energy policy of Finland wikipedia , lookup
Life-cycle greenhouse-gas emissions of energy sources wikipedia , lookup
Energy harvesting wikipedia , lookup
Energy efficiency in transport wikipedia , lookup
Distributed generation wikipedia , lookup
Energy policy of the European Union wikipedia , lookup
Negawatt power wikipedia , lookup
Energy in the United Kingdom wikipedia , lookup
United States energy law wikipedia , lookup
Conservation of energy wikipedia , lookup
Energy efficiency in British housing wikipedia , lookup
Energy Independence and Security Act of 2007 wikipedia , lookup
Name: ___________________________________ Period: _____ Date: ____________________ Ch 12 Pretest: Work, Power, Energy Part 1: Matching. Place the letter of the best word by each definition. 1. _______ The unit used to measure energy 1 N . 1m 2. _______ energy from fission (splitting atoms) or fusion (combining atoms) 3. _______ the ability to do work 4. _______ no energy can get in our out or the amount is so small it can be ignored 5. _______ exerting a force for a distance; F x d 6. _______ heat energy, usually made from friction 7. _______ the amount of useful work a system does; what energy is not lost to “useless” forms (heat, sound) 8. _______ when energy can freely enter or leave a system 9. _______ light energy, like from the sun A. closed system B. efficiency C. elastic potential energy D. gravitational potential energy E. kinetic energy F. Joules G. Law of conservation of energy H. nuclear energy I. open system J. power K. radiant energy L. thermal energy M. Watts N. work O. energy 10. _______ energy stored by compressing or stretching something 11. _______ energy can not be created or destroyed; it only changes form 12. _______ units used to measure power; equal to 1 J/1 s 13. _______ energy when something is in motion 14. _______ the work you do and the amount of time in which you do it W/t 15. _______ energy of position; energy due to where you are Use the formula W = F x d to solve the following equations. Show your work and be sure to use correct units and sig figs. 16. _____________________ Joan moves her dresser, which weighs 53 N a distance of 4.32 m. How much work did she do? 17. _____________________ Felippe did 175.64 J of work moving an object 9.17 m. How much mass does the object have? 18. Jose moves a box 5 m with 60 N of force in 10 seconds. Felicia pushes against a car, for 3 minutes, but fails to move it. Who did more work? Explain. 19. In the problem above, who used more power, Jose or Felicia? Explain. Use the formula P = W/t to solve the following equations. Show your work and be sure to use correct units and sig figs. 20. _____________________ Gorge did 5150 J of work in 73 seconds. How much power did he use? 21. _____________________ Antoinette’s car used 45,166W of power to do 432.5 J of work. How long did it take? 22. – 23. What is efficiency of a system and how can we improve it (in general and specifically)? 24. How are energy and work related? A parked car starts at the top of a hill and rolls down and up the other side, equally as high…. 25. – 26. Does it reach the top? Explain. 27. – 28. Where does it have the most gravitational potential energy? Explain 29. – 30. Where does it have the least gravitational potential energy? Explain. 31. – 32. Where does it have the most kinetic energy? Explain 33. – 34. Where does it have the least kinetic energy? Explain. 35. – 37. I’m going bowling. I pick up the ball, go through my approach and throw it. It hits the pins and I get 9. Describe all the forms of energy involved and what makes them change form (what does the work). Use the following formulas for the following problems. Show your work and use the correct units and sig figs. Use 10.0 m/s2 for the acceleration due to gravity. KE = ½ mv2 GPE = mgh EPE = ½ kx2 38. _____________________ In the problem above, if my ball has a mass of 7 kg and I throw it 2.01 m/s, how much KE does it have? 39. _____________________ If I have a mass of 91 kg and I am 0.55 m above ground on the Moon, what is my gravitational potential energy (g on the moon is 1.6 m/s2) 40. _____________________ The spring constant of a certain spring is known to be 400. N/m. If I stretch the spring .75 m how much EPE does it have? 41. _____________________ There’s a 1250 kg car at the top of a hill 75 m high. The brake fails and it starts to roll. How fast will it roll at the bottom if all GPE is converted into KE? 42. - 45. Label each type of energy as it is transformed to a new type of energy in the picture below. 46. – 48. Label as many transformations of energy as you can in the picture below. 49. - 52.Name two places where energy is “lost.” Explain how/why it is “lost” and how we can improve that. Name: ___________________________________ Period: _____ Date: ____________________ Ch 12 Pretest: Work, Power, Energy Part 1: Matching. Place the letter of the best word by each definition. F___ The unit used to measure energy 1. ___ 1 N 1m A. closed system B. efficiency or fusion (combining atoms) C. elastic potential energy D. gravitational potential . H__ energy from fission (splitting atoms) 2. ___ O___ the ability to do work 3. ___ A___ no energy can get in our out or the 4. ___ amount is so small it can be ignored N___ exerting a force for a distance; F x d 5. ___ L___ heat energy, usually made from friction 6. ___ B___ the amount of useful work a system 7. ___ does; what energy is not lost to “useless” forms (heat, sound) I 8. ___ ___ when energy can freely enter or leave a system energy E. kinetic energy F. Joules G. Law of conservation of energy H. nuclear energy I. open system J. power K. radiant energy L. thermal energy M. Watts N. work O. energy K___ light energy, like from the sun 9. ___ C___ energy stored by compressing or stretching something 10. ___ G___ energy can not be created or destroyed; it only changes form 11. ___ M___ units used to measure power; equal to 1 J/1 s 12. ___ E___ energy when something is in motion 13. ___ J___the work you do and the amount of time in which you do it W/t 14. ___ D___ 15. ___ energy of position; energy due to where you are Use the formula W = F x d to solve the following equations. Show your work and be sure to use correct units and sig figs. 230 J______ Joan moves her dresser, which weighs 53 N a distance of 16. ___ W=Fxd 4.32 m. How much work did she do? 53 x 4.32 228.96 (2 sf) 19.2 N _____ Felippe did 175.64 J of work moving an object 9.17 m. How 17. ____ W=Fxd much mass does the object have? 175.64 = F x 9.17 19.15376227 (div by 9.17) (3 sf) 18. Jose moves a box 5 m with 60 N of force in 10 seconds. Felicia pushes against a car, for 3 minutes, but fails to move it. Who did more work? Explain. Jose did 60 x 5 = 300J Felicia did 0 N, because the car didn’t move 19. In the problem above, who used more power, Jose or Felicia? Explain. Jose used 300/10 = 30 W Felicia used 0 W (because she did 0 work) Use the formula P = W/t to solve the following equations. Show your work and be sure to use correct units and sig figs. 71 W______ Gorge did 5150 J of work in 73 seconds. How much power 20. ____ P = W/t did he use? 5150/73 70.54794521 (2 sf) .009576 s ________ Antoinette’s car used 45,166W of power to do 21. _______ 432.5 J of work. How long did it take? P = W/t 45,166 = 432.5/t 45,166t = 432.5 (mult by t) (div by 45,166) .009575787 (4 sf) 22. – 23. What is efficiency of a system and how can we improve it (in general and specifically)? A measure of energy “lost” due to friction If you decrease friction, you increase efficiency…use oil, smooth surfaces, etc. to improve. 24. How are energy and work related? Energy and work are “opposites sides of the same coin” you use energy to do work. We measure energy by the amount of work done. That’s why they use the same units… J. A parked car starts at the top of a hill and rolls down and up the other side, equally as high…. 25. – 26. Does it reach the top? Explain. No. It “loses” some of its energy to heat and sound because of friction and air resistance. 27. – 28. Where does it have the most gravitational potential energy? Explain At the top of the hill…it’s the highest up. 29. – 30. Where does it have the least gravitational potential energy? Explain. At the bottom of the hill. It’s the lowest point. 31. – 32. Where does it have the most kinetic energy? Explain At the bottom of the hill. It’s moving the fastest. 33. – 34. Where does it have the least kinetic energy? Explain. At the top, before it moves. It has 0 J of KE if it’s not moving. 35. – 37. I’m going bowling. I pick up the ball, go through my approach and throw it. It hits the pins and I get 9. Describe all the forms of energy involved and what makes them change form (what does the work). Chemical kinetic I do work on the ball to pick it up, move and throw it Kinetic (ball) kinetic (pins) The ball does work to make the pins move Kinetic (ball) Sound Friction does work to make sound Use the following formulas for the following problems. Show your work and use the correct units and sig figs. Use 10.0 m/s2 for the acceleration due to gravity. KE = ½ mv2 GPE = mgh EPE = ½ kx2 10 J_________ In the problem above, if my ball has a mass of 7 kg and I 38. ______ throw it 2.01 m/s, how much KE does it have? 2 KE = ½ mv = .5 (7) (2.01)2 *** order of operations says you do the square first!*** = 14.14035 (1 sig fig) 80. J______ If I have a mass of 91 kg and I am 0.55 m above ground on 39. _______ the Moon, what is my gravitational potential energy (g on the moon is 1.6 m/s2) GPE = mgh = (91)(1.6)(.55) = 80.08 (2 sig figs) 110 J ________ The spring constant of a certain spring is known to be 40. ________ 400. N/m. If I stretch the spring .75 m how much EPE does it have? 2 EPE = ½ kx = .5 (400)(.75)2 *** order of operations says you do the square first!*** = 112.5 (2 sig figs) 39 m/s______ There’s a 1250 kg car at the top of a hill 75 m high. The 41. _____ brake fails and it starts to roll. How fast will it roll at the bottom if all GPE is converted into KE? GPE = KE mgh = ½ mv2 (1250)(10.0)(75) = .5(1250)v2 *** note that since mass is on both sides, it cancels out. 750 = .5v2 1500 = v2 v = 38.72983346 (2 sig figs) 42. - 45. Label each type of energy as it is transformed to a new type of energy in the picture below. picture is already labeled here 46. – 48. Label as many transformations of energy as you can in the picture below. B D C A A B C D chemical to heat and light heat to kinetic kinetic to electrical electrical to light and heat 49. - 52.Name two places where energy is “lost.” Explain how/why it is “lost” and how we can improve that. A Heat lost to radiation Insulate the boiler B lost to heat through friction Oil the machine C lost to heat through friction Oil the machine