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Tuesday May 21

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Overview Energy 1.Motion 2.Object 3.Potential 4.Mechanical Energy 5.Chemical 6.Elastic 7.Chemical 8.Gravitational 9.Elastic 10.Gravitational

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The nature of energy 1.Energy of a spinning bicycle wheel 2.Energy stored in food 3.Energy stored in a boulder on a …. 4.Energy stored in a stretched string 5.Energy that is stored 6.Less 7.More 8.Energy 9.Joule 10.Potential,kinetic 11.Potential 12.Chemical

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Chapter Test Continued 18)A 19)D 20)B 21)C 22)A 23)B 24)D 25)C Understanding Concepts 1.A. PE=mgh=10(9.8)(1.5)=147 J B. PE=mgh=(10)(9.8)(1)= 98 J 2. KE= ½ mv 2 =.5(10)(10)(10)= 500 J 3. KE=PE=147 J

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There are two types of potential energy problems. A 4.5 kg dictionary sits on a 4.0 m high shelf. Find its potential energy. PE= mgh PE= 4.5 (9.8) 4 PE= 176.4 J A 12-N copper ball sits on a church stepple 40 m above the ground. Find its potential energy. PE=WH PE= 12(40) PE=480 J

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An automobile to be transported by ship is raised 7.0 m above the dock. If its gravitational potential energy is 66000 J, find its mass. Given Solution

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An automobile to be transported by ship is raised 7.0 m above the dock. If its gravitational potential energy is 66000 J, find its mass. Given H= 7.0 m A= 9.8 m/s/s PE= 66 000 J M= ? Solution PE=mgh M=PE/gh M= 66 000/9.8(7) M= 960 kg

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The world record for pole vaulting is 6.15 m. If the athlete’s gravitational potential energy is 4,942 J, what is his mass? Given Solution

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The world record for pole vaulting is 6.15 m. If the athlete’s gravitational potential energy is 4,942 J, what is his mass? Given H= 6.15 m PE= 4942 J G= 9.8 m/s/s M=? Solution PE=mgh M=PE/gh M= 4942/9.8(6.15) M= 82 kg

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Find the kinetic energy of a.045 kg hockey puck traveling at 45 m/s. KE= ½ mv 2 KE= ½ (.045) (45)(45) KE= 45.56 J

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A baseball is pitched with a speed of 35 m/s. Calculate its kinetic energy if it has a mass of 0.146 kg? Given Solution

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A baseball is pitched with a speed of 35 m/s. Calculate its kinetic energy if it has a mass of 0.146 kg? Given M= 0.146 kg V= 35 m/s KE= ? Solution KE= ½ mv 2 KE= (.5)(0.146)(35)(35) KE= 89 J

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A “ping-pong” ball has a mass of.00245 Kg and can be given a speed of 4.0 m/s. Find its kinetic energy? Given Solution

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A “ping-pong” ball has a mass of.00245 Kg and can be given a speed of 4.0 m/s. Find its kinetic energy? Given M= 0.00245kg V= 4 m/s KE= ? Solution KE= ½ mv 2 KE= (.5)(0.00245)(4)(4) KE= 0.0196 J

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Potential Energy Worksheet 1. PE=mgh or PE=WH 2. Joule (J) 3. PE=WH PE=12(21) PE=252 J

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Potential Energy Worksheet 4. PE=WH PE=79(20) PE= 1580 J 5.PE=WH PE=190(45) PE=8550 J

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Potential Energy Worksheet 6.PE=WH PE= 966(72) PE= 69, 552 J 7.PE=mgh PE=5(9.8)12) PE= 588 J

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Kinetic and Potential Energy Worksheet 1 KE= ½ mv 2 KE= ½ 2.1(30*30) KE= 945 J 3 KE= ½ mv 2 KE= ½ (1120) 40 * 40 KE= 8,960,000 J

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Kinetic and Potential Energy Worksheet 7.D 8.A 9.D 10.Friction.

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Energy problems Worksheet 1. KE= ½ mv 2 KE= =.5(3) (5)(5) KE= 37.5 J

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Energy problems Worksheet 2. PE=mgh PE= 6.5(9.8)(5) PE=166 J

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Energy problems Worksheet KE= ½ mv 2 M= 2 KE/v2 M= 2(173)/(3.8 * 3.8) M= 24 J

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Energy problems Worksheet PE=mgh H=PE/mg H=328/(7.5)(9.8) H=4.5m

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Energy problems Worksheet 5. KE= ½ mv 2 KE= ½ 30 (2*2) KE= 60 J KE= ½ mv 2 KE= ½ 60 (2*2) KE= 120 J It doubles.

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Energy problems Worksheet 6. KE= ½ mv 2 KE= ½ 30 (2*2) KE= 60 J KE= ½ mv 2 KE= ½ 30 (4*4) KE= 240 J It is quadrupled.

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Energy problems Worksheet 7.PE= mgh PE= 4(9.8)(2) PE=78.4 J J PE=mgh PE= 4(9.8)(4) PE= 156.8 J It doubled.

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Energy problems Worksheet 8. KE= ½ mv 2. 4.2 m/s KE= ½ 12 (3*3)

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Energy problems Worksheet 9. KE= ½ mv 2 2KE= m (52*52) m= 72 kg

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Energy problems Worksheet 10. PE= mgh PE= 0.49(9.8)(3.6) PE=17.3 J PE=mgh PE= 0.49(9.8)(1.5) PE= 7.2 J Decreased by 10.1 J

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