Simple Machines Physics Mrs. Coyle. What are some simple machines? Lever Incline Plane Pulley.
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Transcript of Simple Machines Physics Mrs. Coyle. What are some simple machines? Lever Incline Plane Pulley.
Simple Machines
PhysicsMrs. Coyle
What are some simple machines?
• Lever
• Incline Plane
• Pulley
Simple Machines
• Multiply the effort force (allows you to use a smaller effort force to raise a heavier object).
• Change the direction of the force.
• Do not reduce the work input.
Archimedes: ”GIVE ME A PLACE TO STAND AND I WILL MOVE THE EARTH”
http://www.math.nyu.edu/~crorres/Archimedes/Lever/leverBigCorners.gif
Lever
Mechanical Advantage
MA= Output Force(Weight of Object)
Input Force (Effort)
• MA shows how much you are multiplying your effort force.
What is the trade off?
• What happens to the effort distance, when a machine multiplies the effort force?
• Answer: Effort distance increases
Ideal Mechanical Advantage
• IMA= Effort Distance (din )
Output Distance (dout )
• IMA is equal to MA in the absence of friction (ideal case).
IMA for a Lever
• IMA= Effort Distance = Effort Arm
Output Distance Load Arm
Problem
What is the ideal mechanical advantage
of the lever shown?
IMA=3
FulcrumLoadEffort
Lever
• http://www.walter-fendt.de/ph11e/lever.htm
Types of Levers
• Type1
• Type 2
• Type 3
Incline Plane
http://www.edinformatics.com/math_science/simple_machines/Inclined_plane.gif
dIN
dOUT
Problem: Which has a greater IMA?
A B
Problem: Find the IMA.
10m5m
Pulleys
Pulleys
Single Fixed Pulley
Ideally:
Win=Wout
Findin= Foutdout
IMA= din /dout =1
Single Moveable Pulley
IMA= 2
Combination of Fixed and Moveable Pulleys
IMA= 2
IMA for Pulleys
• The IMA of pulleys can quickly be found by counting the number of lifting strands.
Question
What is the IMA of the following pulleys?
Efficiency• Efficiency indicates the percentage of the
input work that was converted to useful work and not lost to friction.
• % eff = (Wout / Win) x 100 %
• % eff = (MA / IMA) x 100 %