6.3 – Simple Machines Guided notes
Objectives Describe and identify examples of the six types of simple machines. Explain how the different types of simple machines make work easier.
Simple Machines A machine that does work with only one movement Two Families Levers – levers, pulleys, & wheel and axle Inclined Planes – inclined plane, screw, & wedge
Lever Bar that is free to pivot about a fixed point Fixed point = fulcrum Input arm is part on which input force is applied Output arm is part that exerts the output force
Classes of Levers First Class Lever Second Class Lever Third Class Lever
First-class Levers Fulcrum is located between input and output forces Multiplies and changes direction of force http://www.sciencebyjones.com/Firce_class_lever_drawing.gif http://www.cool-science-projects.com/images/man-and-lever.jpg
Second-class Levers Output force is located between input force and fulcrum Always multiplies force http://cache.eb.com/eb/image?id=63039&rendTypeId=4
Third-class Levers Input force is between output force and fulcrum Doesn’t multiply force but does increase distance over which force is applied
3rd class lever Input force- your hand squeezes the stapler Output force- the staple goes through the papers Fulcrum
Lever & Ideal MA Calculating ideal mechanical advantage (IMA) of a lever: IMA = length of input arm divided by length of output arm
Pulley A grooved wheel with a rope, simple chain, or cable running along a groove Modified first-class lever The point in the middle of the wheel is the fulcrum The rest of a wheel acts like the rigid arm. http://www.technologystudent.com/gears1/pulley7.htm
Types of Pulleys Fixed = attached to something and doesn’t move Force is not multiplied but direction is changed IMA = 1
Types of Pulleys Movable = has one end of the rope fixed and the wheel free to move Multiples force IMA = 2
Types of Pulleys Block & Tackle = system of pulleys consisting of fixed and movable pulleys IMA = number of ropes supporting the weight
Block and Tackle Pulley website
Wheel & Axle Machine with two wheels of different sizes rotating together Modified lever
Wheel & Axle IMA = radius of wheel divided by radius of axle Gears are modified forms
Inclined Plane Sloping surface that reduces the amount of force required to do work
Inclined Plane IMA = length of slope (input distance) divided by height of slope (output distance) Less force is required if ramp is longer and less steep
Screw Inclined plane wrapped in a spiral around a cylindrical post
Wedge Inclined plane with one or two sloping sides http://kmoddl.library.cornell.edu/stillImages/Clark/small/003.jpg
Compound Machine Uses a combination of two or more simple machines
Cool Links Simple Machines
In-Class Assignment/Homework 6.3 Reinforcement WKT