Simple Machines

Simple Machines

• Physics

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

• A simple machine consisting of a rigid bar pivoted on a fixed point and used to transmit force,
•  as in raising or moving 
• a weight at one end
•  by pushing down on the other.

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

• Fulcrum

• Load

• Effort

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.

• 10m

• 5m

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.