What is Sphere ?

A metal crystallizes in a body centred cubic structure. If 'a' is the edge length of its unit cell, 'r' is the radius of the sphere. What is the relationship between 'r' and 'a' ?

A thin hollow sphere of mass m is completely filled with a liquid of mass m . What the sphere rolls with a velocity v, kinetic energy of the system is (neglect friciton)

A sphere of radius 0.350m, temperature 27.0^(@)C , and emissivity 0.850 is located in an environment of temperature 77.0^(@)C . At what rate does the sphere (a) emit and (b) absorb thermal radiation ? (c ) What is the sphere's net change in energy in 3.50 min ?

The volume of a sphere s 8 times that of a another sphere. What is the ratio of their surface areas?

Radius of hemisphere is twice that of a sphere. What is the ratio of total surface area of hemisphere and sphere ?

A particle of mass m starts to slide down from the top of the fixed smooth sphere. What is the tangential acceleration when it break off the sphere ?