A force $\vec{F} = \alpha\hat{i} + 3\hat{j} + 6\hat{k}$ is acting at a point $\vec{r} = 2\hat{i} - 6\hat{j} - 12\hat{k}$. The value of α for which angular momentum about origin is conserved is :

Question

Dr. Abubacker · Accepted Answer

[Solution] Torque $\vec{r} 	imes \vec{F} = 0$ needs $\vec{F} \parallel \vec{r}$: $\frac{\alpha}{2} = \frac{3}{-6} \Rightarrow \alpha = -1$. Answer (2).

Q. A force $\vec{F} = \alpha\hat{i} + 3\hat{j} + 6\hat{k}$ is acting at a point $\vec{r} = 2\hat{i} - 6\hat{j} - 12\hat{k}$. The value of α for which angular momentum about origin is conserved is :

Explanation

Reviewed by Dr. Abubacker

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