Question

a railway engine of mass (m) moves along a horizontal track with uniform speed (v). the total resistive force acting on the engine is (f). which of the following is the power of the engine? a. (\frac{f}{mv}) b. (fv) c. (\frac{mv}{f}) d. (\frac{v}{f})

Explanation:

Step1: Analyze the force situation

Since the engine moves with uniform speed, the driving - force $T$ of the engine is equal to the resistive force $F$, i.e., $T = F$.

Step2: Recall the power formula

The power formula is $P = T\times v$. Substituting $T = F$ into the formula, we get $P=Fv$.

Answer:

B. $Fv$