Question

A body of moment of inertia $5kg{m}^2$ rotation with an angular velocity 6 rad/s has the same kinetic energy as a mass of 20 kg moving with velocity of .........

• A. 5 m/s
• B. 4 m/s
• C. 3 m/s
• D. 2 m/s

Answer 1

Answer: (C)

3 m/s

Given that $\frac{1}{2}I{\omega }^2=\frac{1}{2}m{v}^2$
$\therefore \frac{1}{2}\times 5kg{m}^2\times 6^{2}rad/s=\frac{1}{2}\times 20kg\times v^2$
$\therefore v^2=9$
$\therefore v=3m/s$