Simple Machines Physics Mr. Berman

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 Load Fulcrum Effort

Lever http://www.walter-fendt.de/ph11e/lever.htm

Types of Levers Type1 Type 2 Type 3

Incline Plane

dOUT dIN http://www.edinformatics.com/math_science/simple_machines/Inclined_plane.gif

Problem: Which has a greater IMA?

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.

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 %