A spherical shell rolls without sliding along the floor. The ratio of its rotational kinetic energy (about an axis through its center of mass) to its translational kinetic energy is:

The ratio  is  

Explanation:

Generally  the Moment of inertia of a spherical object (shell) is mathematically represented as

Where m is  the mass of the spherical object

       and   r is the radius  

Now the the rotational kinetic energy can be mathematically represented as

Where   is the angular velocity which is mathematically represented as

=>          

So

Generally the transnational  kinetic energy of this motion is  mathematically represented as

So  

total distance travelled = 60 miles

total time taken =1.5 hours

average speed = total distance / total time

60 / 1.5

= 40

therefore, average speed = 40 m/h

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