Instantaneous power delivered by a force is best expressed as:
A$\vec F \times \vec v$
B$\vec F \cdot \vec v$
C$\dfrac{\vec v}{\vec F}$
D$\vec F \cdot \vec a$
Answer & Solution
Correct answer: B. $\vec F \cdot \vec v$
Instantaneous power is the dot product of force and instantaneous velocity, $P=\vec F\cdot\vec v$. The cross product would not represent rate of doing work; only the component of force along velocity contributes to power.
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