5.1.6—P = W / t
- Syllabus
- 9702–2028–2029
- Objective
- 5.1.6
- Level
- AS
Use P=W/t when work is transferred over a known time
For a process with work W completed in time t, average power is P=W/t. Rearranging gives W=Pt or t=W/P.
Keep time in seconds for watts and identify whether W is useful work or total input work before substituting.
A 1.2 kW lift doing 36 kJ of work takes 30 s if its power is constant.
A larger power does not mean more total work unless the operating time is also considered.
ConceptA-Level CAIE Physics AS