Work Power Simple Machines Energy

Work Formula: Work = Force x Distance Work is done on an object when the object moves in the same direction in which the force is exerted. Formula: Work = Force x Distance Units: Work is measured in Joules (J) Force is measured in Newtons (N) Distance is measured in meters (m)

Power Power is the rate of transfer of energy or the rate at which work gets done. Power = Work / Time Power = Watts (W) Work = Joule (J) Time = seconds (s)

Pulley A pulley is a simple machine made of a grooved wheel with a rope or cable wrapped around it.

Types of Pulleys Single Fixed Pulley: attached to the structure, like a flag pole Does not change the amount of force applied Does change direction of the force

Types of Pulleys Single Movable Pulley: this pulley is attached to an object you wish to move Decreases the amount of input force needed Does not change the direction of the force.

Types of Pulleys Block and Tackle: combination of fixed and moveable pulleys Decreases input force even more than a moveable pulley

MA = Output force / Input force Mechanical Advantage MA = Output force / Input force MA also equals the number of sections of rope that support the pulley

Inclined Plane An inclined plane is a flat, sloped surface. An inclined plane allows you to exert your input force over a longer distance

Ideal Mechanical Advantage MA = Length of the incline divided by the height of the incline .

Levers A lever is a rigid bar that is free to pivot, or rotate, at a fixed point The fixed points that a lever pivots on is called a fulcrum

Ideal Mechanical Advantage MA = Distance from fulcrum to input force ÷ Distance from fulcrum to output force Input Force Output Force

Types of Levers Levers are classified according to the location of the fulcrum relative to the input and output forces 1st Class 2nd Class 3rd Class

Examples of Levers Third Class

Three Other Simple Machines Wheel and Axle – a machine consisting of a wheel that turns an axle so that the two parts rotate together. Wedge – a machine with at least one slanting side ending in a sharp edge. Screw – a machine that contains an inclined plane wrapped around a post.

Compound Machines A machine that is made of two or more simple machines.

Energy Energy is the ability to do work or cause change. Kinetic energy is the energy an object has due to its motion. Formula: KE = ½ mv2 Ex: a ball dropped off of a ledge, a bike going up a hill and down a hill Potential energy is stored energy that results from the position or shape of an object. Ex: holding a ball at the top of a ledge, a bike at the top of the hill

Gravitational Potential Energy (GPE) is the energy related to an objects height. The higher an object is raised the more GPE. Formula: GPE = Weight (N) x Height (m)

Elastic Potential Energy Elastic potential energy is the energy associated with objects that can be stretched or compressed.

Conservation of Energy According to the Law of Conservation of Energy, energy cannot be created or destroyed it changes forms. Example: In a pendulum system, energy changes occur between potential and kinetic energy. Most forms of energy can be transformed into other forms. Example: A toaster transforms electrical energy into thermal energy.