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Lever Fulcrum Lab
Question: Where is the best place to put a fulcrum in a first class lever to
lift heavier loads?
Lever Fulcrum Lab
Question: Where is the best place to put a fulcrum in a first class lever to
lift heavier loads?
Hypothesis: If a fulcrum is placed closer to the load, then the
load will be ___________ to lift because _________.
Lever Fulcrum Lab
Question: Where is the best place to put a fulcrum in a first class lever to
lift heavier loads?
Hypothesis: If a fulcrum is placed closer to the load, then the
load will be ___________ to lift because _________.
Materials: Meter stick, 3 weights, Spring Scale, pencil
Lever Fulcrum Lab
Question: Where is the best place to put a fulcrum in a first class lever to
lift heavier loads?
Hypothesis: If a fulcrum is placed closer to the load, then the
load will be ___________ to lift because _________.
Materials: Meter stick, 3 weights, Spring Scale, pencil
Lever Fulcrum Lab
Procedure:
1. Put a pencil under the 80 cm mark of a meter stick to act as
a fulcrum.
2. Place one mass at the 0 cm mark. Hang the spring scale on
the other end, off the edge of the table. Pull down and record
the force needed to lift the mass in your data table.
3. Repeat step 2 with two masses.
4. Repeat step 2 with three masses.
5. Move the pencil so that it is under the 60 cm mark and
repeat steps 2-4.
6. Move the pencil so that it is under the 40 cm mark and
repeat steps 2-4.
Lever Fulcrum Lab
Data:
80 cm Fulcrum
Force (N)
1 mass
2 masses
3 masses
60 cm Fulcrum
Force (N)
40 cm Fulcrum
Force (N)
Lever Fulcrum Lab
Analysis:
1. Where is the best place the fulcrum when the load is
heavy? WHY?
2. Draw a diagram of a 1st, 2nd, and 3rd class lever.
Give an example of each (Reference p. 428 of
textbook).
3. What is the difference between each class of lever?
Lever Fulcrum Lab
Analysis:
4. The number of times a machine multiplies the effort force is the
mechanical advantage of the machine. To calculate the mechanical advantage
(MA), you divide the resistance force by the effort force.
a. A worker applies an effort force of 10 N to pry open a window
that has a resistance of 500 N. What is the mechanical advantage of
the crowbar?
b. A carpenter uses a claw hammer to pull a nail from a board. The
nail has a resistance of 2500 N. The carpenter applies an effort
force of 125 N. What is the mechanical advantage of the hammer?
Lever Fulcrum Lab
Analysis:
5. You can also use the lengths of the arms of a lever to find the mechanical
advantage of the lever. The length of the effort arm is the distance from the
fulcrum to the point where effort force is applied. The length of the resistance arm
is the distance from the fulcrum to the point where the resistance force is applied.
a. You use a crowbar 140 cm long as a lever to lift a large rock. The
rock is 20 cm from the fulcrum. You push down on the other end
of the crowbar. What is the MA of the lever?
b. Draw a diagram of the lever from the previous question showing
the placement of the fulcrum and the direction of the effort force
and resistance force.
Conclusion
You know the four parts!
Restate purpose
Summarize procedure
Explain Results (connect to hypothesis)
Errors/Modifications