Final answer:
Option 3, P = Fv/Δt, is not a valid power equation because power is the product of force and velocity (P = Fv), without dividing by time. The correct unit for power is the watt (W), equivalent to one joule per second.
Step-by-step explanation:
Power in physics is the rate at which work is done or energy is transferred. In equation form, average power P for work W done over a time Δt is expressed as P = W/Δt. The unit for power in the International System of Units is the watt (W), which is equivalent to one joule per second (1 W = 1 J/s).
Considering the options given in the question:
- P = W/Δt is a valid expression for power, where W is work and Δt is the time interval.
- P = Fd/Δt can also be considered a valid expression for power if you recognize that work done W is equal to the force F times distance d, therefore this can be rewritten as P = (Fd)/Δt = W/Δt.
- P = Fv/Δt is not a standard equation for power. Normally, power is the product of force and velocity, without dividing by time.
- P = Fv is indeed the correct equation when power is related to constant force F and constant velocity v, meaning the force is in the direction of the velocity.
Therefore, option 3) P = Fv/Δt is not a valid equation for power.