Name:
S# _____ P# _____
Date:
Title: ____________________________________________________________________________
Purpose:
To study how the position of the fulcrum, resistance force, and effort force,
affect the mechanical advantage of first, second, and third class levers.
Hypothesis:
Make a prediction of the mechanical advantage for each class of lever & give reasons for your
prediction.
1st Class: As distance from F to R increases, the MA will
2nd Class: As distance from F to R increases, the MA will
3rd Class: As distance from F to R increases, the MA will
Data and Observations:
Fulcrum
Position
(cm)
Distance
from F to E
(cm)
First Class Lever Data Table
Distance
Resistance
Effort
from F to R
Force (N) Force (N)
(cm)
Ideal
Mechanical
Advantage
Real
Mechanical
Advantage
Distance
from F to E
(cm)
Second Class Lever Data Table
Distance
Resistance
Effort
from F to R
Force (N) Force (N)
(cm)
Ideal
Mechanical
Advantage
Real
Mechanical
Advantage
Distance
from F to E
(cm)
Third Class Lever Data Table
Distance
Resistance
Effort
from F to R
Force (N) Force (N)
(cm)
Ideal
Mechanical
Advantage
Real
Mechanical
Advantage
70
70
70
Resistance
Position
(cm)
10
10
10
Effort
Position
(cm)
90
90
90
IMA = Distance from the Fulcrum to the Effort ÷ Distance from the Fulcrum to the Resistance
RMA = Resistance Force ÷ Effort Force
Analysis
Draw a graph for each class of lever.
Dist. F to R on the x-axis and mechanical advantage on the y-axis.
Each graph will have a line for the ideal mechanical advantage and a line for the real mechanical
advantage. Don’t forget to include appropriate labels and titles!
Conclusion:
1. For the first class lever, did the effort force become larger or smaller when you
moved the resistance force closer to the fulcrum?
2. For the second class lever, did the effort force become larger or smaller when you
moved the resistance force closer to the fulcrum?
For the third class lever, did the effort force become larger or smaller when you
moved the resistance force closer to the fulcrum?
3. How do third class levers differ from the other two classes? Can you think of a
benefit of using third class levers?
4. Imagine that you are attempting to pry up a boulder using a pole as a lever and a
small stone as a fulcrum. State which class of lever this would be and how you
can tell. Would you choose a long pole or a short one for the task?