5.1.7—P = Fv and use it to solve problems
- Syllabus
- 9702–2028–2029
- Objective
- 5.1.7
- Level
- AS
For constant-speed motion, mechanical power is P=Fv
When a force component F acts along an object’s velocity v, power transferred is P=Fv; more generally use the parallel component.
Use the resultant or driving force specified by the problem and keep the direction/sign clear. This relation follows from work per time because v=s/t.
A 400 N driving force moving a vehicle at 15 m s⁻¹ supplies 6.0 kW of mechanical power.
P=Fv is not P=ma; it relates force to energy-transfer rate and requires the velocity component along the force.
ConceptA-Level CAIE Physics AS