PYQ NEET- Work Energy And Power L-2

Question: A particle moves with a velocity $(5 \hat{i}-3 \hat{j}+6 \hat{k}) \mathrm{ms}^{-1}$ horizontally under the action of constant force $(10 \hat{\mathrm{i}}+10 \hat{\mathrm{j}}+20 \hat{\mathrm{k}}) \mathrm{N}$. The instantaneous power supplied to the particle is :#

A) $200 \mathrm{~W}$

B) Zero

C) $100 \mathrm{~W}$

D) $140 \mathrm{~W}$

Answer: $140 \mathrm{~W}$#

Solution:#

$$ \begin{aligned} & P=\vec{F} \cdot \vec{V} \ & P=(10 \hat{i}+10 \hat{j}+20 \hat{k}) \cdot(5 \hat{i}-3 \hat{j}+6 \hat{k}) \ & P=50-30+120 \ & P=140 \mathrm{~W} \end{aligned} $$