Download Power is the rate of doing work (or transferring energy), or the ratio

Power is the rate of doing work (or transferring energy), or the ratio of work
done to the time interval required to do the work. You can also calculate
power using the product of the prime mover and a rate. The equations for
calculating power in mechanical, fluid, and electrical systems are listed in the
table below.
Power =
Energy System
Prime Mover
work done
time interval
Work Done
Power
Mechanical
Linear
Force (F)
W = FΔ d
Pwr =
Rotational
Torque (τ)
W=τθ
Pwr =
Fluid
Electrical
Pressure (P)
or Pressure
Difference
(Δ P)
Potential
Difference
(ΔV)
Constant pressure:
W = PΔV
Steady state,
constant density:
W = –VΔ P
W = qΔV
Pwr =
Pwr =
Pwr =
FΔ d
Δt
τθ
Δt
= Fv
= τω
PΔV
Δt
VΔ P
Δt
q ΔV
Δt
•
= PV
•
= VΔ P
= IΔV
(Note: In fluid systems, ΔV is the change in volume. In electrical systems,
ΔV is the potential difference or voltage.)
•
In thermal systems, power is the same as heat flow rate, Q . Although we did
not use the term power, you studied heat flow rate in Section 3.4.
C HAPTER 6
SUMMARY
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