Q. A force of $2\widehat{i} + 3\widehat{j} + 4\widehat{k}\ N$ acts on a body for 4 second, produces s displacement of $\left( 3\widehat{i} + 4\widehat{j} + 5\widehat{k} \right)m$. The power used is
A) $9.5\ W$
B) $7.5\ W$
C) $6.5\ W$
D) $4.5\ W$
Explanation
(a) $P = \frac{\overrightarrow{F}.\overrightarrow{s}}{t} = \frac{\left( 2\widehat{i} + 3\widehat{j} + 4\widehat{k} \right).(3\widehat{i} + 4\widehat{j} + 5\widehat{k})}{4} = \frac{38}{4} = 9.5\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.