Question

A force $\overset{\rightarrow}{F}$ = a$\widehat{i}$ + $3\widehat{j}$ + 6$\widehat{k}$ is acting at a point $\overset{\rightarrow}{r}$ = $2\widehat{i}$ – 6$\widehat{j}$– $12\widehat{k}$. The value of 'a' for which angular momentum is conserved is –

• A. 0
• B. 1
• C. – 1
• D.

Answer 1

Answer: (C)

– 1

Answer 2

Angular momentum will be conserved if t = 0

i.e. $\overset{\rightarrow}{r}$ × $\overset{\rightarrow}{F}$ = 0

$\frac{a}{2}$ = $\frac{3}{–6}$ = $\frac{6}{–12}$

\ a = – 1