• question_answer A body having moment of inertia about its axis of rotation equal to $3\text{ }kg-{{m}^{2}}$is rotating with angular velocity equal to 3 rad/s. Kinetic energy of this rotating body is the same as that of body of mass 27 kg moving with a speed of A)  1.0 m/s                        B)  0.5 m/s            C)    1.5 m/s             D)    2.0 m/s

Kinetic energy of rotating body $=\frac{1}{2}I{{\omega }^{2}}=\frac{1}{2}\times 3\times {{3}^{2}}=13.5\,J$ Kinetic energy of translating body $=\frac{1}{2}m{{u}^{2}}$ $\therefore$$\frac{1}{2}m{{u}^{2}}=13.5$or $\frac{1}{2}\times 27{{u}^{2}}=13.5$or $u=1\,m/s.$