Simple Machines: The Inclined Plane Lab
Introduction:
A simple machine can be used to make work easier. This doesn’t mean that you can get
by with less work. If fact, you always will have to do more work when you use a simple
machine than if you don’t use one!
Remember: a simple machine reduces the force you have to use; it does not reduce the
amount of work you must do. With simple machines we are able to reduce the force that must
be used by exerting that force through a larger distance. When the force is less we say the job
is “easier.”
You have learned that scientists describe the helpfulness of simple machines in terms of
Mechanical Advantage. A machine’s mechanical advantage is the number of times the
machine multiplies force. (It compares the input force with the output force) For example,
imagine that you had to push a 500 N weight up a ramp and only needed to push with 50 N of
force the entire time. The mechanical advantage would be the output force (500 N) divided by
the input force (50 N) for a mechanical advantage of 10. A machine that has a mechanical
advantage that is greater than 1 can help move or lift heavy objects because the output force is
greater than the input force.
There are two types of mechanical advantage. An Ideal Mechanical Advantage (if
everything worked perfectly) and the Actual Mechanical Advantage (the mechanical
advantage you actually get).
People also tend to be interested in the efficiency of the simple machines they use.
Efficiency compares how much work goes into a simple machine with how much work comes
out.
In this lab you will be finding the mechanical advantage and efficiency of an inclined
plane. You will see if changing the angle (by changing the height) of the inclined plane or
adding mass to the resistance will change any of these.
Remember to record all data and answer all questions on the lab write-up.
Purpose:
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In your own words, state the purpose of this lab.
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Lab Formulas:
Work = Force X Distance
Distance In (length of ramp)
IMA = ------------------------------------Distance Out (height of ramp)
Efficiency (in %) =
Lab Materials:
Inclined plane
Cart
Force Out (weight of cart)
AMA = ------------------------------------Force In (effort force)
Work Out
------------------- X 100
Work In
2 ring stands
meter stick
ring stand clamp
5 N & 10 N spring scale
Procedure:
1) Set up the inclined plane so the height of the ramp is 30 centimeters. (I recorded the
height on the lab write-up for you).
2) Measure the length of the ramp (inclined plane) in meters; record.
3) Attach one end of the string to the cart and the other end to the spring scale.
4) Measure the weight of the cart.
5) Pulling parallel (along the ramp angle), pull the cart up the ramp at a constant speed
with the spring scale. Record the effort force needed.
Calculations: Use the formula to calculate the work done in lifting the cart 30 cm without
the ramp. (That will be the “Work Out” in your calculations.) Then calculate the ideal
mechanical advantage (IMA), actual mechanical advantage (AMA), the work required to
raise the cart (“Work In”), and the efficiency of the ramp.
Predictions:
1) Will the ideal mechanical advantage increase, decrease, or remain the same if you
make the inclined plane steeper?
2) Will the efficiency increase, decrease, or remain the same if you make the inclined
plane steeper?
6) Now, raise the ramp height to 45 centimeters and fill in the data table for that height.
Analysis and Conclusions: Answer the questions on the lab write-up.
Note, This lab was adapted from the James Madison Memorial High School ISP and your textbook.
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Simple Machines: The Inclined Plane Lab
Purpose:
Name: _________________
________________________________________________________________
________________________________________________________________
Lab Materials:
Predictions:
1) Will the ideal mechanical advantage increase, decrease, or remain the same if you
make the inclined plane steeper? ____________________________________
2) Will the efficiency increase, decrease, or remain the same if you make the inclined
plane steeper? _____________________________
Data:
Ramp (30 cm height)
Ramp (45 cm height)
.3 m
.45 m
Height
Length
Weight of cart
Effort force
Work (no ramp) = Work Out
IMA
AMA
Work In
Efficiency
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Lab Formulas:
Simplified Procedure:
Analysis and Conclusions:
1) How does a ramp (inclined plane) make a job easier? ___________________________
______________________________________________________________________
2) Does it require more or less force to lift the cart using the ramp?___________________
3) Is more or less work done in lifting the cart using the ramp? _____________________
4) How does the ideal compare with the actual mechanical advantage?________________
______________________________________________________________________
5) What force causes a difference between the ideal and actual mechanical advantage?
______________________________________________________________________
How could this force be reduced?___________________________________________
6) Which is easier (requires less force): using a short, inclined plane or using a long notso-steep inclined plane? ________________________________________________
7) Which requires less work: using a short, inclined plane or using a long not-so-steep
inclined plane? _______________________________________________________
8) List the six types of simple machines:
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____________________
_____________________
____________________
____________________
_____________________
____________________
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Simple Machines: Levers Lab
Introduction:
Simple Machines do not let you get away with doing less work. You must
do exactly as much work, plus a little more to overcome friction.
The advantage of the simple machine is that it makes the task easier
because the machine reduces the force required or changes the direction in which
the force is applied. A simple machine may make a task easier, but they always
require more work IN than you can get back OUT.
All machines are made up of one or more simple machines. Levers are
simple machines that change the amount of force needed to lift objects and can
change the direction in which the lifting force is applied. For example, an object
can be lifted upward by pulling downward. You have experience with this effect
on the playground. If your friend is sitting on the far end of the teeter-totter and
you want to get on, you pull downward in order to lift them up off the ground.
Levers can be divided into three groups or “classes” depending upon the
relative position of three points on the lever...these three points are the fulcrum,
the effort force, and the resistance force.
The Fulcrum - is the fixed point of the lever, the pivot point.
The Effort -
is the place on the lever where you are applying your force
- pushing or pulling. It is the place where you are putting
your work IN to the lever. It is the force which we must
apply to accomplish the task using the simple machine.
The Resistance - is the place on the lever where the object which we
want to move is located. It is the place where the work that
comes OUT of the machine is accomplished. It is the force
which must be overcome in order to accomplish the task
without using the simple machine.
In this lab you will become familiar with the three classes of levers and be
able to identify how the use of a lever changes the nature of the work.
In other words, the ADVANTAGE that can be gained by using a lever.
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Part 1: Identifying the class of a lever
Look at the diagrams of the three classes of levers below. Use your textbook, pages 106
& 107 to help you place a check on the lines in the boxes.
FIRST CLASS LEVERS:
The fulcrum is always located between the effort and resistance forces.
What is possible…
Gain In...
Loss In...
____
Force
____
____
Distance ____
SECOND CLASS LEVERS:
The resistance force is always located between the fulcrum and the effort force.
What is possible…
Gain In...
Loss In...
____
Force
____
____
Distance ____
THIRD CLASS LEVERS:
The effort force is always located between the fulcrum and the resistance force.
What is possible…
Gain In...
Loss In...
____
Force
____
____
Distance ____
If we were to summarize the positions of the three points on the lever, we would find
that each class of lever always has the same point located between the other two points.
First Class Lever...
Second Class Lever...
Third Class Lever...
(F)ulcrum
(R)esistance force
(E)ffort force
Can you see that the three classes of levers are always F-R-E (free) for the taking?
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Procedure:
Part 2: The operation of a first class lever
1) Use a meter stick, clamp, and hangers to assemble a first class lever. The fulcrum should
be located at the 50 cm mark.
2) Hang a 500 gram resistance mass at the 80 cm mark. Note that mass is not equal to a
force, however it is proportional to the force called weight. Using Newton's 2nd Law
formula (F=ma), the 500g mass weighs 4.9 N. This is the resistance force. I filled it in for
you on the lab report.
3) Hang a spring scale upside down at the 20 cm mark.
4) Will this setup let you apply less force than the resistance? Predict the Mechanical
Advantage on the lab report. Choose >1, <1, or 1.
5) Use the spring scale to measure and record the actual effort force in the data table. When
upside down, the spring scale is not properly calibrated, you must add on 0.3 Newtons.
6) Repeat steps 2 - 5 with the 500 gram mass moved to the 90 cm mark.
7) Repeat steps 2 - 5 with the 500 gram mass moved to the 60 cm mark.
8) Calculate the actual mechanical advantage. AMA= output force divided by input force
Part 3: The operation of a second class lever
Assemble a second class lever with the fulcrum at the 90 cm mark.
2) Hang a 500 gram resistance mass at the 30 cm mark, the spring scale at the 10 cm mark.
3) Record the resistance force (its still the same) and predict the mechanical advantage.
4) Measure the actual effort force required to make this lift. DO NOT add 0.3 Newtons to the
reading on the scale, it is calibrated to work in this position.
5) Repeat steps 2 - 4 with the 500 gram mass moved to the 50 cm mark.
6) Repeat steps 2 - 4 with the 500 gram mass moved to the 70 cm mark.
7) Calculate the actual mechanical advantage.
1)
Part 4: The operation of a third class lever
1) Assemble a third class lever with the fulcrum at the 50 cm mark.
2) Hang a 500 gram resistance mass at the 5 cm mark, the spring scale at the 30 cm mark.
3) Record the data in the first three columns and predict the mechanical advantage.
4) Measure the actual effort force required to make this lift..
5) Repeat steps 2 - 4 with the 500 gram mass moved to the 15 cm mark.
6) Repeat steps 2 - 4 with the 500gram mass moved to the 25 cm mark.
7) Calculate the actual mechanical advantage.
Analysis & Conclusions: Answer the questions on the lab write-up.
Adapted from: Integrated Science Program James Madison Memorial High School
ISP Online Document Page: http://www.madison.k12.wi.us/jmm/isp/ispindex.htm
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Name: __________________
Simple Machines: Levers Lab
Purpose:
________________________________________________________________
________________________________________________________________
Lab Materials:
Data & Calculations:
Part 2: 1st Class Levers
Resistance
Force
(N)
4.9
Predicted Mechanical
Advantage
(choose: >1, <1, or 1)
Effort
Force
(N)
Actual
Mechanical
Advantage
4.9
4.9
Part 3: 2nd Class Levers
Resistance
Force
(N)
4.9
Predicted Mechanical
Advantage
(choose: >1, <1, or 1)
Effort
Force
(N)
Actual
Mechanical
Advantage
4.9
4.9
Part 4: 3rd Class Levers
Resistance
Force
(N)
4.9
Predicted Mechanical
Advantage
(choose: >1, <1, or 1)
Effort
Force
(N)
Actual
Mechanical
Advantage
4.9
4.9
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Analysis & Conclusions:
1. For a first class lever, make a diagram showing the arrangement of the resistance, effort,
and fulcrum that would obtain the greatest mechanical advantage possible?
2. For a second class lever, make a diagram showing the arrangement of the resistance, effort,
and fulcrum that would obtain the greatest mechanical advantage possible?
3. For a third class lever, make a diagram showing the arrangement of the resistance, effort,
and fulcrum that would obtain the greatest mechanical advantage possible?
5. Of the three classes of levers, which ones allow you to do less force than would have to be
done without using the simple machine? Explain you answer.
6. Of the three classes of levers, which ones allow you to do less work than would have to be
done without using the simple machine? Explain you answer.
7. Respond to the statement...
“Give me a lever long enough and a place to stand, and I will move the world.”.
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