Question

A force of 7i+6k n makes a body move on a rough plane with a velocity of 3j+4k m/s calculate the power

Answer 1

F = Ki + Lj + Mk and v = Pi + Qj + Rk then F ∙ v = K∙P + L∙Q + M∙R

In your question F = 7i + 0j + 6k and v = 0i + 3j + 4k so, P = 7∙0 + 0∙3 + 6∙4 = 0 + 0 + 24 = 24 Watt.

Time, speed, temperature and power are scalars whereas weight and acceleration are vectors.

Answer 2

Given F = 7i + 6k N

         v = 3j + 4k m/s

Power P = Force x Velocity

            P = F . v

               = (7i + 6k) (3j + 4k)

               = 24 watts