# Work, Energy & Momentum

 Energy Property of a system to do work. Kinetic Energy Definition, formula, SI units is energy of motion.  Objects that have mass and are moving with some velocity will have K. K=(1/2)*m*(v^2) Joule (J) = kg*m2/s2 Potential Energy. Definition, formula, SI units Object is said to have a potential energy when it has a potential to do something.  U=mghJ= kg*m2/s2 Total Mechanical Energy is a sum of object's potential and kinetic energies. E=U+K The first law of thermodynamics energy is never created or destroyed. Conservation of Mechanical Energy E of the system is conserved in absence of friction.  The sum of a system's potential energy and kinetic energy will be constant. Work -- definition, formula, SI units Work is not a form of energy, but a process by which energy is transferred from one system to another. W=F*d*cosθ J=N*m=kg*m2/s2 θ is an angle btw force and displacement vectors how many ways are there to transfer energy from one system to another. Work and Heat Power -- definition, formula, SI units the rate at which energy is transferred from one system to another. P=W/t Watt (W) = J/s Work-Energy Theorem W-E Theorem offers a direct relationship btw work done on an object by all forces and the change in its kinetic energy: Wnet=ΔK=KEf - KEi Momentum Formula and SI Units Quality of objects in motion.p=mvkg*m/s All objects that have momentum, also have... Inertia -- the tendency of the objects to resist changes in their motion and momentum. Impulse: Definition, Formula, SI Units Impulse is a change in momentumI=FΔt=Δp=mvf - mvikg*m/s Elastic Collisions  Define Give an Example p conserved? KE conserved? Where objects don't stick together.  E.g. Billiard ballsp conserved:  p1i + p2i = p1f + p2fKE conserved: KE1i+KE2i = KE1f+KE2f Inelastic Collisions Define Give an Example p conserved? KE conserved? Where objects don't stick togetherE.g. two cars crashingp conserved:  p1i + p2i = p1f + p2fKE not conserved: ΔKEi > ΔKEf Completely Inelastic Collisions Define Give an Example p conserved? KE conserved? Where objects stick togetherE.g. 2 cars crashing and becoming one. or two molecules colliding and becoming one (covalent bond).p conserved:  p1i + p2i = (m1+m2)*vfKE not conserved: ΔKEi > ΔKEf In what type of collisions is momentum conserved? In all collisions Mechanical advantage makes it easier to accomplish a given amount of work since the input (applied) force necessary to accomplish work is reduced. The distance through which the reduced input force must be applied, however, is increased by the same factor. Inclined planes, levers, and pulleys provide the benefit of mechanical advantage. Center of Mass Is a point within the object at which all the object's mass could be represented as a single particle. X=(m1x1+m2x2+....)/(m1+m2+...) Authorit2007 ID222446 Card SetWork, Energy & Momentum DescriptionWork, Energy & Momentum Updated2013-06-06T16:00:02Z Show Answers