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Simple Machine Lab and Reference Sheet
Identify the problem:
To better understand the advantages and applications of simple machines
by utilizing the inclined plane, wedge, screw, pulley, and lever (we will
explore wheel and axles by building balloon cars and possibly pasta
mobiles).
Research:
Simple machines are devices which can be used to do work more easily.
Simple machines do this by 1.)Decreasing effort force required, 2.) changing
the direction of the effort force, and / or 3.) changing the distance over
which the effort force is applied. All simple machines are derivatives of the
lever and the inclined plane.
The following vocabulary is used in this lab:
Effort-
The force applied to move a resistance-measured with a spring
scale.
Effort distance-
the distance the effort (spring scale) moves.
Resistance-
the force of resistance which is being moved.
Resistance distance-
the distance the resistance (load) moves.
Actual Mechanical
Advantage (AMA)-
the factor by which the machine actually does multiply the effort
force in a real situation AMA= Resistance Force/Effort Force
Efficiency-
the ratio of (work output/work input) x 100 %. A statement of the
effectiveness of the machine-how much energy is conserved/lost.
Fulcrum-
the pivot point of a lever.
Hypotenuse-
the longest side of a triangle
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Equations:
Work input=Effort Force x Effort Distance
Work output= Resistance Force x Resistance Distance
AMA= Resistance Force/Effort Force
Efficiency= (work output/work input) x 100 %
Hypothesis:
What advantages is there in using the simple machines?
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Materials :
(these are already set up around the room)
Meterstick
Pulleys
Spring Scale
1 kg masses
String
Scissors
Marker/piece of
Block of wood
paper
Screwdriver/screws Fulcrums/hangers
Protractor
Ramp/board
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Part 1: Inclined Planes (Caution: Heavy weight used)s
Inclined planes are flat, slanted surfaces that multiply force. They are a type of simple machine
that a resistance (a weighted object) is moved on.
Procedures:
1.
2.
3.
4.
Measure the angle of the inclined plane using a protractor.
Place the 1 kg mass at the bottom of the inclined plane.
Pull the mass up the incline using the spring scale-noting the force required.
Measure the distance to the top of the incline up the ramp. Measure the
height. Record.
5. Vertically lift the mass from the desk to the top of the incline-record the
force required.
6. Complete the data table below and do calculations.
7. Repeat the procedure.
Data:
Trial Angle
1.
2.
Height (Rdist)
Length (Edist)
Effort Force
Resistance
Force
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Data Calculations
Trial Angle
Work Input
Work Output
AMA
Efficiency
Analysis:
1. How did the efficiency compare between the angles of the incline?
Explain.
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Conclusion
If you want to build an incline plane that requires the least amount of
force to push something up, how would you build it? Why?
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Part 2 Wedges
Wedges are usually shaped like two small inclined planes glued
together. They are simple machines that move a resistance. They usually
have a “cutting” or “splitting” ability.
Procedure:
1. Measure the width of the wedge and the length of the wedge and
record in the data table.
2. Calculate the Ideal Mechanical Advantage of each wedge.
Data:
Wedge Angle
Width (Rdist)
Length (Edist)
Analysis:
1. Which wedge required the least force to separate the blocks?
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IMA
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2. Is it better to have a long thin wedge or a short and wide wedge if you want
to cut thought something easily? Why?
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3. Why do sharp knives cut better than dull knives?
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4. List some items that are made of wedges. (need all 5)
1. ___________________
2. ___________________
3. ___________________
4. ___________________
5. ___________________
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Part 3 Screws (CAUTION: Sharp edges and sharp wood pieces)
Screws are inclined planes wrapped around a cylinder. They’re like twisted
wedges. They, too, are simple machines that move a resistance.
Procedure:
1. Cut an 8.5” x 11” pieces of paper in half diagonally to make a paper inclined
plane.
2. Darken or color the hypotenuse edge with a marker.
3. Place a pencil inside the parallel to the shortest side, with the marker edge
facing out.
4. Roll the pencil so that the paper wraps around it. Describe what you see.
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5. Take the block of wood. Take the screw with the least number of threads
per area and use the screwdriver to screw it into the wood.
6. Screw the other screws in and compare how difficult it is to screw in those
with more threads versus those with less threads. Compare in the table
below.
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Data:
Threads
Description of Difficulty
Few
Many
Analysis:
Which screws were more difficult to screw in?_____________________________
Conclusion:
1. If you had very dense wood, would you use screws with more or less
threads per area? Why?
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2. If you had to mount something heavy to the wall, which screws would you
use? Why?
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Part 4: Lever (Caution: Heavy weight used)
A lever is a rigid bar that rotates about a fixed point.
Procedure:
1. Review the classes of levers, and sketch a first, second and third class lever
below.
First Class
Second Class
Third Class
2. Build an lst class lever using the meter sticks and clamps. Locate the fulcrum
30 cm from one end of the meter stick.
3. Hang a 1 kg mass on the short end of the meter stick.
4. Use your spring scale to pull down on the long end of the lever noting both
the force required and the actual distance you pulled the lever down. Also
note how far the resistance was lifted in process.
5. Fill in the data chart below and do the calculation chart.
6. Repeat the experiment using a 2nd class lever-putting the fulcrum at the
end of the meter stick and hanging the 1 kg mass 40 cm from the fulcrum.
Place the spring scale at the far end of the meter stick (opposite the
fulcrum).
7. Repeat the experiment using a 3rd class lever-just switch the location of the
1 kg mass and the spring scale.
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8. Data Table:
Type of Effort Distance
lever
1st
Resistance
Distance
Effort Force
Resistance
Force
2nd
3rd
Data calculations: Use provided terms on reference sheet.
Type of lever
Work Input
Work Output
AMA
Efficiency
1st
2nd
3rd
Analysis:
1. Compare and contrast the efficiency of each class lever. Which is the most
efficient? Why?
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2. What is the advantage of using each class lever? What is the disadvantage
of each?
Class levers
Advantages
Disadvantages
1st
2nd
3rd
3. What did Archimedes mean when he said, “give me a lever long enough
and I can move the world.” Be specific.
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Part 5 Pulleys: (Caution: Heavy weight used)
A pulley is a simple machine made of a grooved wheel with a rope or cable
wrapped around it.
1. Draw and label the following pulley systems.
Fixed
Movable
Block and Tackle
1. Build a fixed pulley system using a 1 kg mass as resistance.
2. Lift the 1 kg mass using the spring scale to pull with. Record the effort
distance, resistance distance, effort force and resistance force in the data
table for the fixed pulley.
3. Repeat the above steps using a moveable pulley and a block and tackle
pulley system.
Data Table:
Type of
Pulley
Fixed
Moveable
Block and
Tackle
Effort Distance
Resistance
Distance
Effort Force
Resistance
Force
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Data calculations: Use provided terms on reference sheet.
Type of
Pulley
Fixed
Work Input
Work Output AMA
Efficiency
Moveable
Block and
Tackle
Analysis Questions:
1. How does the number of supporting ropes relate to the mechanical
advantage of each pulley system?
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2. What advantages can be achieved by using a pulley system? How can work
be made easier by using pulleys?
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Part 6 Wheel and Axle
A wheel and axle is a machine made of two circular or cylindrical objects that are
fastened together and that rotate about a common axis.
1. Draw an example of a wheel and axle. Label.
2. How is ideal mechanical advantage of a wheel and axle calculated?
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