Q 11-05-180JEE MainJEE Main 2019 (10 Jan, Shift 2)Easy
A particle which is experiencing a force, given by $\vec F = 3\hat i - 12\hat j$, undergoes a displacement of $\vec d = 4\hat i$. If the particle had a kinetic energy of $3\ \text{J}$ at the beginning of the displacement, what is its kinetic energy at the end of the displacement?
Answer: (B) $15\ \text{J}$
$W = \vec F\cdot\vec d = 3\times4 = 12\ \text{J}$. By the work-energy theorem, $K_f = 3 + 12 = 15\ \text{J}$.
Solution by Sreeraj P, M.Sc Physics