Do Now: 1.An object which weighs 10 N is dropped from rest from a height of 4 meters above the ground. What is its total energy when it has free-fallen.

Do Now:1. An object which weighs 10 N is dropped from

rest from a height of 4 meters above the ground. What is its total energy when it has free-fallen 1 meter with respect to the ground?

2. During a certain time interval, a 20-N object free-falls 10 meters. The object gains how many Joules of kinetic energy during this interval?

Do Now:1. During a certain time interval, a 20-N object

free-falls 10 meters. The object gains how many Joules of kinetic energy during this interval?

Do Now (2/13/12):

•Make a list of concepts to be covered on tomorrow’s test.

Ms. Timson’s

Review to Conquer Physics

Rules of the Game• There will be tribes, as divided by the teacher• For each problem which appears on the slide, the tribe will be able to work

together to vote on one answer given only the time which will be written on the slide.

• Tribes cast their answer using their voting cards only in the time allowed.• Each team with a correct answer is allowed to cast one vote to remove

another tribe from the island. The teacher will have each tribe cast their vote simultaneously by writing the color of the tribe they are voting for on their white board. The teacher will then remove tribes from the island.

• The teacher will track which tribes are in and which tribes are out of the game with signs on the board.

• If a tribe is voted out, they can reenter the game by answering the next question correctly to reenter. They will NOT receive a vote for that question but must wait until the next question.

• Winning tribes will be those still on the island at the end of the game.• ***The teacher will be the final judge of any conflicts or confusions – and

remember, be respectful and be honest!

1. The unit of work, Joule, is dimensionally the same as:

A. Newton/secondB. Newton/kilogramC. Newton second∙D. Newton meter ∙

10 seconds

2. Which of the following quantities refers to the rate at which work is done?

a. heatb.kinetic energyc. efficiencyd.Power

10 seconds

3. A girl pushes a box 5 m by applying a 25 N horizontal force. What work does she do?

A.10 JB. 25 JC. 125 JD. 550 J

25 seconds

4. Which of the following refers to a machine’s ratio of output work to input work?

A.IMA B. efficiency C. mechanical advantage D. Reliability

20 seconds

5. If the mechanical advantage of a pulley system is .95, what effort force must be exerted to lift a 20.0 N box at constant velocity?

A.22 N B.21 N C.20 N D. 19 N

20 seconds

6. What angle between the force applied on an object and its displacement will allows for maximum work done on the object?

A.0B.45C.70D.90

15 seconds

7. A rope is used to pull a metal box 10 m across the floor with a force of 500 N. The rope is held at an angle of 60° with the floor. How much work does the puller do?

A.3 x 105 JB.5.0 x 103 JC.2.5 x 103 JD.2.5 x 102 J

1 minute

8. In which of the following situations is work done equal to zero?

a. picking up a book on the floor and putting it on top of the desk

b.pushing a chair across the room while applying a horizontal force on it

c. leaning against a concrete wall d.going down from the first floor to the second

floore.coming in late and not doing the drill

1 minute

9. How fast would a 200-kg meteorite have to travel to have the same energy as a 20,000-kg meteorite traveling at 100 m/s?

A.500 m/s B.5000 m/sC.1000 m/s D.10,000 m/s

1 minute

10. The main difference between kinetic energy and potential energy is that

A. kinetic energy involves position and potential energy involves motion.

B. kinetic energy involves motion and potential energy involves position.

C. although both energies involve motion, only kinetic involves position.

D. although both energies involve position, only potential involves motion.

30 seconds

11. A force of 8 N is exerted on a 1 kg mass at rest for 2 m, causing it to move. What is the change in the object’s kinetic energy?

A.2 JB. 16 JC. 8 JD. 64 J

45 seconds

12. Which energy transformation occurs as a book falls from the top of your book shelf?

A. the book’s potential energy and kinetic energy decreases

B. the book’s potential energy increases and it’s kinetic energy decreases

C. the book’s potential energy decreases and it’s kinetic energy increases

D. the book’s potential energy and kinetic energy increases

20 seconds

13. A 3.00 kg toy falls from a height of 10.0 m. Just before hitting the ground, what will be its kinetic energy?

A.98.0 J B. 0.98 JC. 294 JD. 29.4 J

1 minute

14. What is the speed of the 3 kg toy that fell from 10 m in the previous problem just before it hits the ground?

A.3.33 m/sB. 14 m/sC. 5.47 m/s D. 30 m/s

1 minute

15. As an object is lowered into a deep hole in the ground, which of the following assumptions must be made in regard to the object’s potential energy?

A. The potential energy decreases. B. The potential energy increases.C. The potential energy remains constant. D. The potential energy increases and then

decreases.

45 s

16. John has an object suspended in the air. It has a mass of 20 kilograms and is 50 meters above the ground. How much work would the object do if it was dropped?

a. 100 jb.1000 jc. 980 jd.9800 j

45 seconds

17. A 2 kg rock loses 350 J of potential energy while falling to the ground. What is the rock's speed just before it strikes the ground?

a. 175 m/sb.350 m/sc. 18.7 m/sd.13.2 m/s

45 seconds

18. A force of 70.0 N is used to slide a 10.0 kg box 5.0 m horizontally from position A to position B. How much work is done on the box?

A) 0 J B) 70 J C)350 J D)500 J E)3500 J

45 seconds

19. A force of 70.0 N is used to slide a 10.0 kg box 5.0 m horizontally from position A to position B. How much potential energy does the box as a result of the work done on it?

A)0 J B) 70 J C)350 J D)500 J E) 3500 J

45 seconds

20. If a 2 kg object undergoes free fall for 50 m, it will lose about ____ J of potential energy.

A)0 B)70 C)100 D)200 E) 1000

45 seconds

A 2.0 kg stone is dropped from the top of a cliff that rises 50.0 meters above ground.

21. What is the potential energy of the stone at the top of the cliff before it is dropped? (Use the ground as the base level.)

A) 40 J B) 100 J C) 400 J D) 1000 J E) 10,000 J

45 seconds

A 2.0 kg stone is dropped from the top of a cliff that rises 50.0 meters above ground.

22. As it falls, what is the kinetic energy of the stone at a height of 30 m from the ground?

A)60 J B) 200 J C) 400 J D) 600 J E) 1000 J AB) 4000 J

45 seconds

A 2.0 kg stone is dropped from the top of a cliff that rises 50.0 meters above ground.

23. As the stone falls it reaches a speed of 20 m/s. What is its kinetic energy at this point?

A)20 J B) 40 J C) 200 J D) 400 J E) 600 J

45 seconds

A 2.0 kg stone is dropped from the top of a cliff that rises 50.0 meters above ground.

24. What is the height of the stone when it has a speed of 20 m/s?

A)3 m B)4 m C) 10 m D)30 m E)E) 40 m

45 seconds

A 2.0 kg stone is dropped from the top of a cliff that rises 50.0 meters above ground.

25. When the stone comes to rest after striking the ground it has neither potential nor kinetic energy. The energy was most likely converted to ______ and ______ . (Enter two answer letters.)

A)electricity B) heat C) light D) magnetism E) Sound 45 seconds

Congratulations!Good luck tomorrow!

I know you can conquer your test