There are three class of levers

First-Class when the fulcrum is closer to the load than to the input force

Second-Class the output force, or load, is between the input force and the fulcrum

Third-Class the input force is between the fulcrum and the load

Pulley a simple machine that consists of a wheel over which a rope, chain, or wire passes

Fixed Pulley only spins. Mechanical advantage = 1

Movable Pulley moves up with the load as the load is lifted. Mechanical advantage = 2

Block and Tackle a fixed pulley and movable pulley are used together.Mechanical advantage = 4 because there are four rope segments and you have to pull the rope 4 m just to lift the load 1 m

Wheel and axle a simple machine consisting of two circular objects of different sizes; the wheel is the larger of the two circular objects

Inclined plane a simple machine that is a straight, slanted surface, which facilitates the raising of loads; a ramp

Wedge a simple machine that is made up of two inclined planes and that moves; often used for cutting

Mechanical advantage is the same with inclined plane

Screw a simple machine that consists of an inclined plane wrapped around cylinder

Compound machine a machine made of more than one simple machine

Chapter 9 Energy and Energy Resources
Section 1 What is Energy?

Energy the capacity to do work

Kinetic energy the energy of an object that is due to the object motion

Potential energy the energy that an object has because of the position, shape, or condition of the object

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