My professor in engineering materials proposed a question an

My professor in engineering materials proposed a question and I was hoping someone out there could give me an explanation: Why do we have one equation for density but two equations for Young\'s modulus? Any help in explaining would be greatly appreciated. Thanks!

Solution

The density of a body is constant and it independent of force where as Youngs Modulus is the value which depends on Force and actually depends on the force acting on it as with variation in SHEAR modulus , Bulk modulus and Poisson ratio so it is unlike density needed another equation to define it as with change in Force the young modulus also depends and varies.