Definitions work The scientific definition of work is

Definitions work - The scientific definition of work is a force exerted over a distance (work = force · distance) energy - The scientific definition of energy is the ability to do work power - The scientific definition of power is the rate at which work is done (power = work time)

Equations and Units work Equation Unit W=F·d joule You must use the force component in the direction of the d when determining the work {1 J = 1 N · m } energy Equation Unit The equation depends on the type of energy joule or kilowatt·hour {1 k. W·hr = 3, 600, 000 J } power Equation P=W t Unit watt {1 watt = 1 J/s } or horsepower {1 hp = 746 watts }

Types of Mechanical Energy KINETIC ENERGY (KE) - energy of motion ( KE = 1/2 mv 2 ) moving objects, sound waves POTENTIAL ENERGY (U) - stored energy There are two types of mechanical stored energy: Gravitational potential energy (UG) - energy stored by gravity ( UG = mgh ) wrecking ball GPE is always a negative and large number when we look at the Earth and an object near its surface – usually, we’re concerned with changes in GPE in a given system, thus mgh. Elastic potential energy (Us) energy stored by an elastic medium ( US = ½ kx 2 ) where: k = spring constant rubber band x = amount of stretch or compression