At any instant of time $t$, the displacement of any particle is given by $2t-1$ (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit):

A 7

B 6

C 10

D 5

The answer is C.

Solution

Instantaneous velocity $v = \frac{ds}{dt} = \frac{d}{dt}(2t - 1) = 2\ ms^{-1}$ Instantaneous power $P = Fv = 5 \times 2 = 10$ W

Concept Instantaneous power from displacement-time relation

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