OBJECT:

To observe what happens when we vary the Fulcrum, Resistance and the Effort in the three classes of levers.

* CAUTION *

This experiment has the potential of eye injury !! Be sure to wear your Safety Goggles at all times.

MATERIALS:

Safety Goggles, Rubber band scale, A one foot or a two foot stand of PVC pipe, Heavy books to be place at the bottom of the stand to weigh down the stand so that it will not move. Small quantity of Copper wire, say 14 gauge or close to that. A two foot PVC pipe with Metric strip glued to it, so the total length of the is about 70 cm, A four inch PVC extension, with bolt and a wing nut.

OBSERVATION AND PROCEDURE:

1. Adjust the Rubber band scale to read zero grams.

2. Construct a First class lever as shown below; you will need some 14 gauge copper wire or close to that gauge for your fulcrum.

3. Adjust the Fulcrum until the distance between the Resistance and the Fulcrum is 5 cm.

4. Now move the Fulcrum to 10 and record the Effort in chart below.

6. Now construct a 2 nd class lever as shown below.

7. Record the weight of the two foot PVC pipe, with out any resistance = ____ g.

8. Now attach the 200 g Resistance as close to 0 cm as you can, weight = _____ g

9. Now, subtact the weight of the two foot PVC pipe ( # 7 ) from the weight you got in ( # 8 ). The answer should be very close to the 200 g ( your answer = ____ g )

10. Now for every answer you get, you should subtact the weight of the Two foot PVC pipe; before you record it.

11. Now, complete the table below by moving the resistance to 5 cm, 10 cm, 15 cm, 20 cm, 30 cm, etc. and record the corrected weight in the table below.

SECOND CLASS LEVER ( A )

R = 200 g	DISTTANCE BETWEEN R & F	0 cm	10 cm	30 cm	40 cm	50 cm
	EFFORT IN GRAMS	___ g	___ g	___ g	___ g	___ g

SECOND CLASS LEVER ( B )

R = 500 g	DISTTANCE BETWEEN R & F	0 cm	10 cm	30 cm	40 cm	50 cm
	EFFORT IN GRAMS	___ g	___ g	___ g	___ g	___ g

12. Now, construct a 3 rd class lever as shown below.

13. Place the Effort at zero cm ( or exactly at the Rubber band scale ) then to 10 cm, etc. from the resistance, record the effort in table below.

THIRD CLASS LEVER ( A )

R = 100 g	DISTTANCE BETWEEN R & F	0 cm	10 cm	30 cm	40 cm	50 cm
	EFFORT IN GRAMS	___ g	___ g	___ g	___ g	___ g

THIRD CLASS LEVER ( B )

R = 200 g	DISTTANCE BETWEEN R & F	0 cm	10 cm	30 cm	40 cm	50 cm
	EFFORT IN GRAMS	___ g	___ g	___ g	___ g	___ g

QUESTIONS:

1. Define Simple Machine.

2. Draw the three classes of levers. Give example of each.

3. Define a Lever.

4. What does the Mechanical Advantage indicate ?

5. What are the two formulas for determining the Mechanical Advantage of a Simple Machine ?

6. Explain the term; Work input = Work output.

7. In which class of lever was the Resistance allowed to move ?

8. In which class of lever was the Fulcrum allowed to move ?

9 In which class of lever was the Effort allowed to move?

10. What was the M. A. of a 1 st class lever ( A ) when R = 500 g and the distance between R & F was 10 cm ( your effort ____ ) ( B ) When R = 500 g and the distance between R & F was 30 cm ( Your Effort ____ ).

11. In the problem above ( A ) when the distance between the R & F was 20 cm; What was the distance between F & E ? ( _______ cm )

12. In a 1 st class lever how is the M. A. related to the distance between R & F and between F & E ?

13. What was the M. A. of a 2 nd Class lever ( A ) When R = 500 g and the distance between R & E was 10 cm ( your Effort ____ ) ? ( B) When R = 500 g and the distance between R & E was 60 cm ( your Effort _____ ) ?

14. In a 2nd Class lever how is the M. A. related to the distance between R & E and between R & F ?

15. The M. A. of a 3 rd Class lever ( A ) when R = 100 g and the distance between E & R was 5 cm ? ( B ) When the R = 100 g and the distance between E & R was 50 cm ?

16. What can you state about the mechanical advantage of a 3 rd Class lever ?

17. What is a gained when force is lost ?

18. What is the formula for determining the efficiency of a simple machine ( Lever ) ?

19. Is it true that in a first-class lever, Effort and Resistance move in opposite directions ?

20. In all second-class levers, the Resistance is located between ___ and ____ .

21. In a third-class lever, the effort is located ______________________.

22. Your arm is an example of which class of lever ? Explain.

23. Why does even the best designed machine have an efficiency of less then 100 per cent ?

24. What percentage of Work put into a machine, that produced as useful work, is called the ____________?

25. How far is a Resistance 5 feet from the fulcrum raised if an Effort 15 feet from the fulcrum is moved down 10 feet ?

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