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Math of Simple Machines. Tuesday July 24, 2007. Ratio and Proportion. Ratio is a fraction. Proportion is the relationship between two quantities with constant ratios or fractions. Work. Anything that pushes or pulls to move an object across a distance. Work (W) = force (F) × distance (d)
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Math of Simple Machines Tuesday July 24, 2007
Ratio and Proportion • Ratio is a fraction • Proportion is the relationship between two quantities with constant ratios or fractions.
Work • Anything that pushes or pulls to move an object across a distance. Work (W) = force (F) × distance (d) W = F*d • Conservation of Energy implies Work In = Work Out + Work Lost to Friction • Ideal Machine does Ideal Work with no work lost to friction
Mechanical Advantage • Consider the work in and work out of a simple machine like an inclined plane : Work in = F1 x d1 Work out = F2 x d2 F2 x d2 = F1 x d1
Efficiency of a Machine • An Ideal Machine has 100% efficiency • What is the relationship between mechanical advantage and efficiency?
Simple Machines • The Lever • The Pulley • The Wheel and Axle • The Inclined Plan • The Wedge (single or double) • The Screw
Force, F2 Load, F1(force of the object desired to move) d1 d2 Lever • A rigid bar that rotates around a fixed point called a fulcrum. • A Load or force is also the gravitational weight
d1 d2 Load, F1 Force, F2 Pulley Fixed Movable ? Movable = Fixed
Raxle Rwheel Wheel and Axle
Load, F1 Force, F2 height, h length, l Inclined Plane
l Force, F2 Load, F1 h SINGLE WEDGE l h Load, F1 Force, F2 DOUBLE WEDGE Wedge
Screw • Modified version of the inclined plane.
Trigonometric Functions • Sine and cosine functions • Sine function • Cosine function