Question

A sphere of uniform density with mass 21 kg and radius 0.8 m is spinning, making one complete revolution every 0.8 s. the center of mass of the sphere has a speed of 8 m/s. (a) what is the rotational kinetic energy of the sphere?

Answer 1

Using the equation;
TE = 1/2mv^2(1+2); where k = 2/5 for a solid sphere; V is the velocity, and m is the mass.
Total energy = 0.5 × 21 × 8² (7/5)
                    = 940.8 J
The rotational kinetic energy of the sphere is 940.8 J