Q 11-05-016NEETJEE MainEAMCET 2013 (Engineering)Easy
The work done by a force $\vec{F} = 2\hat{i} - \hat{j} - \hat{k}$ in moving an object from the origin to a point whose position vector is $\vec{r} = 3\hat{i} + 2\hat{j} - 5\hat{k}$ is
Answer: (B) $9$ units
$$W = \vec{F}\cdot\vec{r} = (2)(3) + (-1)(2) + (-1)(-5) = 6 - 2 + 5 = 9\ \text{units}$$
Solution by Sreeraj P, M.Sc Physics