A particle moves with a velocity    1 v 5j 3j 6k ms      under influence of a contact force  F 10i 10j 20k N.      THe instantaneous power applied to the particle is

P = 200 W

Explanation:

The expression for the power is

        P = W / t

the job

       W = F d

we substitute

      P = F d / t

      P = F. v

We apply this equation to our case where the velocity is

 v = (5 i + 3j + 6k) m / s

and the force is

 F = (10i + 10j +20 k) N

we substitute in the power equation, remember that the scalar product of the unit vectors is

i.i = j.j = k.k = 1 and the other products are zero

    P = 10 5 + 10 3 + 20 6

    P = 200 W