Mechanical power
Power measures the rate of work or energy transfer.
Key knowledge
Average power is work divided by the time interval; instantaneous mechanical power is dW/dt. For a force acting at a point moving with velocity v, its power is F·v. A force perpendicular to that velocity transfers no mechanical energy through that point even if it changes the direction of motion.
Values and equations
P_average=ΔW/Δt; P=dW/dt=F·v
- P,P_average
- Instantaneous and average power W
- W,ΔW
- Work and work over the interval J
- t,Δt
- Time and nonzero interval duration s
- F
- Applied force N
- v
- Velocity of its application point m s⁻¹
Conditions and scope
- Use the velocity of the force’s application point in the same reference frame.
- Extended deformable contacts can transfer energy through multiple points; the centre-of-mass velocity alone need not describe all work. Signed power distinguishes delivery from removal of energy.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read §7.4 average/instantaneous definitions7.10–7.11 and force–velocity power derivation. Retain application-point and reference-frame scope; no claim that all energy transfer is point-force work.
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Entry details
Permanent link to this entry ↗- Record identity
- foundation-physics-mechanical-power
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions