Page Description Equation
kinetic energy K=12mv2
joule. SI unit for work and energy 1Nm=1J
200 watt. SI unit for power 1W=1Js
200 horsepower. Unit of power in British engineering system 1hp=746W
200 kilowatt hour. Common unit of energy 1kWh=3.60MJ
work done by constant force W=Fd=Fdcosθ
work done by constant force in direction of displacement W=Fd, where θ=0
work done by constant force in direction opposite displacement W=Fd, where θ=180
work done by force that varies with position. E.g. conservative forces like gravity or a spring. Note, Fx is the component of F along the x-axis and the force at position x??? Wx=xfxiFxdx, where Fx=Fcosθ
work-kinetic energy theorem Wx=xfxiFxdx=xfximvdv=12mv2f12mv2i=TfTi=ΔT
work done by friction Wk=fkd
net work with friction and other forces W=Wotherfkd
work done by a spring Ws=xfxikxdx=12kx2i12 kx2f=KiKf=ΔK
work done by a force applied to a spring (pull or push) Wapp,s=Ws=xfxikxdx=12kx2f12kx2i=KfKi=ΔK
power P=dWdt=Fdsdt=Fv