Name: ______Period: _____ Date: ______Self Assessment: Energy & Calculations

1. Energy is the ability to ______and is measured in ______.

There are a lot of different forms of energy. Match the columns, then give an example of each on the blank provided. 2. _____ stored in chemical bonds A. chemical ______3. _____ light (radiant) energy B. elastic PE ______4. _____ objects in motion C. electricity ______5. _____ moving electrons D. electromagnetic ______6. _____ moving molecules E. gravitational PE ______7. _____ energy stored by position F. heat/thermal ______8. _____ stored by compression/ G. kinetic ______stretching something 9. _____ when air molecules are H. nuclear ______compressed/stretched 10. _____ energy within an atom (gained by I. sound ______splitting atoms)

11. Any time energy transfers from one form or object to another ______is being done and some energy is ______due to friction/air resistance changing energy into ______and/or ______. 12. The amount of energy lost compared to the original amount is called the ______. Think about a person on a swing…(Drawing it may help.) 13. Where is gravitational potential energy the most? The least?

14. Where is kinetic energy the most? The least?

15. What other forms of energy are there? Explain where in the scenario they occur.

16. What is doing the work to transform the energy back and forth? 17. If the person doesn’t push any more, why do they not go to the same height each time? Problems: Show your work and place your answer on the blank. Be sure to use correct units and sig figs. Use 10.0 m/s2 for g. GPE = mgh KE = 1/2mv2 EPE = 1/2kx2

18. ______An apple has a mass of .75 kg and is 2.5 m high on the tree. How much GPE does it have?

19. ______An orange has 20.15 J of GPE. It is 1.97 m off the ground, what’s its mass?

20. ______How much KE does an object with a mass of 1500 kg have if it’s moving 35 m/s?

21. ______If a car has a mass of 2135 kg has 35,152 J of KE, how fast is it moving?

22. ______I compress a spring with a constant of 4.5 N/m a displacement of 10 cm, how much EPE did I store? (careful…)

23. ______I stretch a rubber band 35 cm and store 12.7 J of EPE in it. What is the spring constant of the rubber band in N/m?

The following all have to do with conservation of energy. One form is being transformed into another. You can solve the problems by setting the two equations equal to each other, filling in what you know and solving for the unknown.

24. ______A 1.5 kg football is thrown up into the air with a velocity of 6 m/s. What is the maximum height it will go to?

25. ______I stretch a catapult down 5 m and place a 3.5 kg rock on it. If the spring constant is 45 N/m, how fast will the rock go when released? Name: ______Period: _____ Date: ______Monday Popquiz: Energy unit so far

1. Energy is the ability to do Work and is measured in Joules . (1 N m/s).

There are a lot of different forms of energy. Match the columns, then give an example of each on the blank provided.

2. _A_ stored in chemical bonds A. chemical __food______

3. _D_ light (radiant) energy B. elastic PE _a spring______

4. _G__ objects in motion C. electricity _runs computer_

5. _C_ moving electrons D. electromagnetic _sunlight_

6. _F__ moving molecules E. gravitational PE _ball on

top of hill_

7. _E__ energy stored by position F. heat/thermal _temperature__

8. _B__ stored by compression/ G. kinetic ___car moving___ stretching something 9. _I__ when air molecules are H. Nuclear _fission/fusion_ compressed/stretched 10. __H__ energy within an atom (gained by I. sound __ singing ___ splitting atoms)

11. Any time energy transfers from one form or object to another __work___

is being done and some energy is __“lost”___ due to friction/air resistance changing energy

into __heat__ and/or __sound__.

12. The amount of energy lost compared to the original amount is called the __efficiency___.

Think about a person on a swing…(Drawing it may help.) 13. Where is gravitational potential energy the most? The least? Most at the top of the swing (highest) Least at the bottom of the swing

14. Where is kinetic energy the most? The least? Most at the bottom of the swing (fastest) Least at the top of the swing (not moving)

15. What other forms of energy are there? Explain where in the scenario they occur. Heat (from air resistance) Sound Chemical (food eaten) Electromagnetic (sunlight)

16. What is doing the work to transform the energy back and forth? Gravity is! It’s the force that pulls you down (change GPE  KE) You are! When you push back up (chemical energy  GPE)

17. If the person doesn’t push any more, why do they not go to the same height each time? Friction/air resistance changes some of the energy into “useless” forms (heat, sound)

Problems: Show your work and place your answer on the blank. Be sure to use correct units and sig figs. Use 10.0 m/s2 for g.

GPE = mgh KE = 1/2mv2 EPE = 1/2kx2

18. ____19 J______An apple has a mass of .75 kg and is 2.5 m high on the tree. How much GPE does it have? GPE = mgh GPE = (.75kg)(10.0 m/s2)(2.5m) 19. _____1.02 kg______An orange has 20.15 J of GPE. It is 1.97 m off the ground, what’s its mass? GPE = mgh 20.15 J =(m)(10.0m/s2)(1.97m)

20. __920000 J_____ How much KE does an object with a mass of 1500 kg have if it’s moving 35 m/s? KE = ½ mv2 KE = ½(1500kg)(35m/s)2 ** be sure to square 35 m/s first**

21. ___5.738 m/s______If a car has a mass of 2135 kg has 35,152 J of KE, how fast is it moving? KE = ½ mv2 35152 J = ½(2135kg)v2

22. ___.02 J______I compress a spring with a constant of 4.5 N/m a displacement of 10 cm, how much EPE did I store? (careful…) **10 cm = .1 m** EPE = 1/2kx2 EPE = ½ (4.5 N/m)(.10m)2 ** be sure to square .1 m first**

23. ___210 N/m__ I stretch a rubber band 35 cm and store 12.7 J of EPE in it. What is the spring constant of the rubber band in N/m? **35 cm = .35 m** EPE = 1/2kx2 12.7 J = ½k(.35m)2 ** be sure to square .35 m first**

The following all have to do with conservation of energy. One form is being transformed into another. You can solve the problems by setting the two equations equal to each other, filling in what you know and solving for the unknown.

24. ____2 m______A 1.5 kg football is thrown up into the air with a velocity of 6 m/s. What is the maximum height it will go to? KE = GPE ½ mv2 = mgh ½(1.5 kg)(6 m/s)2 = (1.5 kg)(10.0 m/s2)h

25. ____20 m/s____ I stretch a catapult down 5 m and place a 3.5 kg rock on it. If the spring constant is 45 N/m, how fast will the rock go when released? EPE = KE ½ kx2 = ½ mv2 ½ (45 N/m)(5m)2 = ½ (3.5 kg) v2