# Week 9

Lab Report                                                    Name: ____________________

Section: ___________________

EXPERIMENT:   Simple Machine – Lever

Experiment 1:

DATA TABLE 1: Fulcrum at _______ cm

Trial

from fulcrumEffort

(Mass)Distance of Effort

from fulcrumRatio:

Effort Distance/

1

1 quarter

1 quarter

2

2 quarters

1 quarter

3

3 quarters

1 quarter

4

4 quarters

1 quarter

Experiment 2: Part 1 – First-class lever:

DATA  TABLE 2: First-class Lever, Fulcrum at _____ m

mMass of

500-g

Spring scaleSpring scale

Force, NEffort

Distance, m

M.A.

1

62g = 0.61N

2

62g = 0.61N

3

62g = 0.61N

Example Data Table

mMass of

500-g

Spring scaleSpring scale

Force, NEffort

Distance, m

M.A.

1

100

1

0.3

62g = 0.61N

10g =0.1N

0.71N

.45

1.41

2

153

1.5

0.3

62g = 0.61N

45g =0.44N

1.05N

.45

1.42

Checking results: Workin = Workout or 1N*0.3m = 0.71N*.45m

*   MA = 1/0.71 = 1.41

Experiment 2: Part 2 – Second-class lever:

DATA TABLE 3: Second-class Lever, Fulcrum at _____ m

mEffort

Force, NEffort

Distance, m

M.A.

Example

1.47

0.2

80g = 0.78N

.90

1.9

1

2

3

4

etc

Experiment 2: Part 3 – Third-class lever:

DATA TABLE 4 (Third-class Lever), Fulcrum at _____ m

MEffort

Force, NEffort

Distance, m

M.A.

Efficiency

1

2

3

Average

Calculations:

1.       In Experiment 1 calculate the ratios of the measured distances; i.e. the rations of Effort Distance/Load Distance

2.       In Experiment 2, Parts 2, 3 and 4 convert grams as needed to Newtons.

3.       In Parts 2, 3, and 4 calculate M.A. for each trial of each lever type.

Questions:

In Experiment 1 you calculated the ratios of the measured distances, i.e. the ratios of Effort Distance/Load Distance.  What is the significance of these ratios?  How did your calculations compare to your expectations?

The spring balance is reasonably accurate for determining the load mass.  However, the spring balance weighs 62 grams. Explain how to use the Workin = Workout principle to verify the mass of the spring balance.

After examining the 1st class lever data what kind of general statement can be made with regards to mechanical advantage and the relationship of load distance to effort distance?

What happens to the mechanical advantage for 2nd class levers as the load moves further away from the fulcrum?

What is the significance of the mechanical advantage of class 3 levers?

What class lever is represented by a fishing pole?  Why?

What kind of lever is represented by an oar used in rowing?  Why?