Q 11-03-009NEETJEE MainEAMCET 2008 (Medical)Easy
Three forces $\vec{A} = (\hat{i} + \hat{j} + \hat{k})$, $\vec{B} = (2\hat{i} - \hat{j} + 3\hat{k})$ and $\vec{C}$ act on a body to keep it in equilibrium. Then $\vec{C}$ is
Answer: (A) $-(3\hat{i} + 4\hat{k})$
Concept. Equilibrium: the three forces add to zero.
Step 1. Solve. $\vec C = -(\vec A + \vec B) = -(3\hat i + 0\hat j + 4\hat k)$.
Answer. $-(3\hat i + 4\hat k)$ (Option A).
Solution by Sreeraj P, M.Sc Physics