Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
A spacecraft at $\hat{\mathrm{i}}+2 \hat{\mathrm{j}}+3 \hat{\mathrm{k}}$ is subjected to a force $\lambda \hat{\mathrm{k}}$ by firing a rocket. The spacecraft is subjected to a moment of magnitude
MathematicsVector AlgebraNDANDA 2018 (Phase 2)
Options:
  • A $\lambda$
  • B $\sqrt{3} \lambda$
  • C $\sqrt{5} \lambda$
  • D None of these
Solution:
2193 Upvotes Verified Answer
The correct answer is: $\sqrt{5} \lambda$
$\begin{aligned} & \vec{\tau}=\vec{r} \times \overrightarrow{\mathrm{F}}=(\hat{i}+2 \hat{j}+3 \hat{k}) \times \lambda \hat{k} \\ &=2 \lambda \hat{i}-\lambda \hat{j} \\ \Rightarrow &|\vec{\tau}|=\sqrt{5} \lambda \end{aligned}$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.