Question

A body of mass 1.5 kg rotating about an axis with angular velocity of 0.3 rad $s^{-1}$ has the angular momentum of 1.8 kg $m^2{s}^{-1}$. The radius of gyration of the body about an axis is :

• A. 2 m
• B. 1.2 m
• C. 0.2 m
• D. 1.6 m
• E. 0.8 m

Answer 1

Answer: (A)

2 m

We know that,
$L=l\omega =M{k}^2\omega$ ...(i)$(\because l=M{K}^2)$
Now put the given value in Eq. (i), we get
$1.8=1.5\times K^2\times 0.3$
$K^2=\frac{1.8}{1.5\times 0.3}$
$K^2=\frac{1.8}{0.45}=4$
$K=2m$