Question

A ring of radius 0.5 m and mass 10 kg is rotating about its diameter with an angular velocity of 20 rad/s. Its kinetic energy is

• A. 10 J
• B. 100 J
• C. 500 J
• D. 250 J

Answer 1

The correct option is D 250 J

Rotational kinetic energy $\frac{1}{2}I{\omega }^2=\frac{1}{2}\left(\frac{1}{2}M{R}^2\right){\omega }^2=\frac{1}{2}(\frac{1}{2}\times 10\times (0.5{)}^2)(20{)}^2=250J$