Monday, December 12, 2016

Activity 67: Energy Notes

Energy Notes

Total Work =  Fd Cos(θ)

KE = ½ mv2

Wnet = ΔKE  = Δ½ mv2 = FnetdCos(θ)

PE = Potential Energy

ΔPE = mgh

Conservative Forces
A “Conservative Force” is once for which work depends only on the starting point and ending point.

We can define potential energy for any conservative force.

PEg = mgh
PEs = ½ kx2

Mechanical Energy = KE + PE

Conservation of Mechanical Energy

When only conservative forces act then:
KEI + PEI = KEf + PEf
Or  KE + PE = constant

Nonconservative forces:
KEi + PEi  + Wnc = PEf + KEf
Wnc = ΔKE + ΔPE

Conservation of Energy

Other forms of energy -> electric, chemical, radiant, nuclear & thermal.

KEi + PEi  + Wnc + OEi = PEf + KEf + Oef

1 kcal = 4184 joules


Power

Power is the rate at which work is done.

Power = Work/Time = Fd Cos(θ)/Time


Units in Watts.

1 Watt= 1 J/s

1hp = 746 Watts







Link to Gravitational Potential Energy Questions








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