Q. The velocity of 2 kg body is changed from $(4\widehat{\mathbf{i}} + 3\widehat{\mathbf{j}})\ ms^{- 1}$. The work done on the body is
A) 9 J
B) 11 J
C) 1 J
D) Zero
Explanation
(b) $v_{1} = \sqrt{4^{2} + 3^{2}} = \sqrt{25} = 5\ ms^{- 1}$
$v_{2} = 6\ ms^{- 1}$
Work done = Increase in kinetic energy
$= \frac{1}{2} \times 2\left\lbrack 6^{2} - 5^{2} \right\rbrack\ J$
$= (36 - 25)\ J = \ 11\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.