Question

A body of mass $ 5 \,kg $ acquires an angular acceleration of $ 10\, rad\, s^{-2} $ by an applied torque of $ 2 \,N m $ . Find its radius of gyration.

• A. $ 2.5\,m $
• B. $ \sqrt{2.5} \,m $
• C. $ \sqrt{0.2}\, m $
• D. $ 0.2\,m $

Answer 1

Answer: (D)

$m=5\,Kg$,
$\alpha=10$ rad $s^{-2}$,
$\tau=2\,N\,m$
Torque, $\tau=I \alpha=mk^{2}\alpha \left(\because I=mk^{2}\right)$
where $k$ is the radius of gyration
$\therefore 2=5\times k^{2}\times10$
or $k^{2}=0.04$ or $k=0.2\,m$