Mechanical
Advantage & Work Lab 2005
*** If you were absent or changed lab partners at all during this lab indicate when and why!!
Your
Task: Investigate what factors determine the mechanical advantage in different
types of simple machines.
For each set up: DRAW A PICTURE!!! Label the forces, distances, angles, and masses.
Calculate Force In, Work In, effort, distance effort moved, resistance ,Force Out, Work out, , distance resistance moved, Ideal and Actual Mechanical Advantage.
Important that the masses be moved at a steady constant rate. Average the force in over several trials. If you pull/push at an angle, remember to adjust for the force in the direction of motion.
INCLINED
PLANE:
Pull/Push a mass up an inclined plane(3-5 angles/surfaces) and compare to lifting.
LEVER. FIRST CLASS: Lever, Resistance, Fulcrum (pull down to lift up)
SECOND CLASS: Effort, Resistance, Fulcrum (pull up at end with weight in middle)
Third Class: Resistance, Effort, Fulcrum (pull up in middle with weight at end)
Using tape, meter stick, string, scales, masses, fulcrum. Determine the mechanical advantage for at least three of each type.
PULLEYS: Try as many different combinations of single, double, triple, with fixed, movable, etc..
See picture
sheet for ideas.
Draw a picture for each and carefully collect data. on the effort, resistance, distance effort moved, distance resistance moved.
*****
CONCLUSIONS: (This is where most of your thinking should be done!!)
With 100% Efficiency, Work In=Work Out or Force times Dist = Force times Dist
Actual Mechanical Advantage = Force Out/Force In
Ideal Mechanical Advantage= Distance In/ Distance Out
For each type of simple machine, find out what is the determining factor in figuring out the mechanical advantage of each.
How would you calculate the mechanical advantage WITHOUT knowing the input and output force? Prove this with your data. Also discuss the efficiency of each machine, and where the work is lost.
Which machines are most efficient?, Which are least efficient? Why?
How is energy transformed in each machine? Find examples of where we use each machine in real life.
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MACHINE
TYPE |
** DIMENSIONS
(angle, arm lengths, string) |
IDEAL
MECHANICAL ADVANTAGE (from
dimensions) |
** FORCE
OUT (Resistance Weight) |
** FORCE
IN (Effort Pull) |
** Resistance
Distance OUT (Height) |
** Effort
Distance IN (Pull) |
ACTUAL
MECHANICAL ADVANTAGE (ForceOut/ Force In) |
Work
Out (ForceOut * Dout) |
Work
In (ForceIn * Din) |
Efficiency (AMA / IMA) |
Efficiency2 (WorkOut / Work
In) |
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ramp IMA= ramp
length/height= 1/ sin (θ) |
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pulley IMA = # strings
pulling up |
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lever IMA= effort arm/resist
arm |
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PICTURES:
First Class Second Class Third Class Lever
RAMPS:
PULLEYS:
