1. 6i N m 2. 6j N m 3. -6i N m 4. 6k N m

Answer: 3. -6i N m Torque vecτ=vec r×vec F . vecτ=2hat k×3hat j=6(hat k×hat j)=6(-hat i)=-6hat i\ N m Since hat j×hat k=hat i , reversing the order gives a minus sign. Answer: option 3.

Topic: Moment of force, torque· Rotational Motion

Find the torque about the origin when a force of 3j N acts on a particle whose position vector is 2k m.

1. $6\hat{i}$ N m

2. $6\hat{j}$ N m

3. $-6\hat{i}$ N m

4. $6\hat{k}$ N m

Doubtly Asked 30 Oct 2026 NEET UG 2020 Practice test neet Save WhatsApp Report

1 answer

Best answer

Answer: 3. $-6\hat{i}$ N m

Torque $\vec\tau=\vec r\times\vec F$.

$$\vec\tau=2\hat k\times3\hat j=6(\hat k\times\hat j)=6(-\hat i)=-6\hat i\ \text{N m}$$

Since $\hat j\times\hat k=\hat i$, reversing the order gives a minus sign. Answer: option 3.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

Was this answer helpful?

Find the torque about the origin when a force of 3j N acts on a particle whose position vector is 2k m.

1 answer

Your answer