What is radius of gyration? It is a constant quantity?

Define radius of gyration. Is ti a constant quantity?

Which one is a vector quantity?

Is speed a scalar quantity?

Define radius of gyration of a rigid body.What is the radius of gyration of a solid sphere of mass 1 kg and radius 50 cm?

Is distance a vector quantity?

Is acceleration a scalar quantity?

What is radius ratio? What is its significance in case of ionic crystal?

Is energy a scalar quantity?

Prove the result that the velocity v of translation of a rolling body (like a ring, disc, cylinder or sphere) at the bottom of an inclined plane of a height h is given by v^2=(2gh)/ (i+k^2^l R^3 Using dynamical consideration (i.e. by consideration of forces and torques). Note k is the radius of gyration of the body about its symmetry axis, and R is the radius of the body. The body starts from rest at the top of the plane.

Is velocity a vector quantity?