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24 Cards in this Set

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~Inclined plane wrapped around a post.
~reduces effort force (Fe) and direction.
Work Output/Input/Efficency
Wo= Fe times Dr
Wi= Fe times De
*input is always greater
Efficiency= Wo/Wi times 100
*Never greater then 100%
Low Friction= high efficiency
Inclined Plane
~Changes the amount of effort force (Fe) and direction.
~2 types
First Class Lever
~The fulcrum is between the effort force and the resistence force
Ex. crowbar, scissors, see-saw
Inclined Plane
A smaller force is used but a larger distance is used.
IMA= length of plane/ height of plane
Ex. steps, ramps
~2 inclined planes back to back
~reduces effort force (Fe) and direction
Second Class Lever
~The resistance force is between the fulcrum and the effort force.
Ex. door, wheel, barrow, nutcracker
Third Class Lever
The effort force is between the fulcrum and resistance force.
Ex. shovel, broom, bat, fishing pole
IMA of a lever
~Can be determined by the effort arm length divided by the resistence arm length
~The MA can be less than one in some cases
Mechanical Advantage
The number of times a machine multipliesthe effort force.
MA=Fr/Fe ( No units)
Fr= resis. Fe= effort
~Is the ideal (without friction) formula which varies with the machine
~Always greater than MA
A machine is a device that helps you do work by changing the size or direction of the force.
A lever is.....
~a rigid bar free to pivot
~the fixed point of the pivot is the called the fulcrum.
~There are three classes of levers depending where the fulcrum is.
~Changes the amount of effort force (Fe) and direction.

~ 3 classes of levers.
IMA of a wheel and axle...
IMA=radius of wheel/ radius of axle
Ex.ferris wheel, water wheels and gears, wheel chair
~Wheel and axle working together
~reduces effort force (Fe) and direction.
Wheel and Axle
~The lever that rotates in a circle
~made of 2 wheels of different sizes (axle is smaller)
~effort force applied to the wheel which moves a greater distance
Wheel and Axel
~several levers working together
~reduces effort force (Fe)
an inclined plane wrapped around a cylinder
IMA= the closer the ridges the greaterthe IMA
Ex. jar lid, screw, drill bit
~2 inclined planes put together
~an effort force is applied to the thicker end and transferred to the thinner end.
~chain, belt, or rope wrapped around a wheel
~changes direction OR amount of force
IMA if A wedge..
The longer and thinner the wedge the greater the IMA
Ex. knife, zipper, wdge
Fixed/Movable Pulley
Fixed Pulley- pulley attached to a stationary structure MA is one because it only changes direction
Movable Pulley- multiplies force
IMA of a pulley...
IMA= # of supportive ropes
Ex. flag pole