Question

For perfectly rigid bodies, the elastic constants, Y,B and n are
(A) Y=B=n=0
(B)Y=B=n=infinity
(C) Y=2B=3n
(D) Y=B=n=0.5

Answer 1

Hint: Use the concept of Hooke's law for the determination of the values of the elastic constant under the various loading conditions. Hooke’s law relates the stress and strain occurring in the object due to the loading.


Complete step by step answer
When load is applied on the body, then its behavior depends on the state, shape and size of the object. The body whose deformation is almost equal to zero under the loading condition is known as rigid body. The body which deforms due to the loading condition is not considered as a rigid body. Due to the loading condition, the generation of stress and strain takes place inside the body, and the relation between the stress and strain occurring in the body is determined with the help of Hooke's law.

The strain produced due to the loading condition on the body can give the value of the elastic constant. Here strain means the change in the shape of the body from its initial shape due to the external loading. The rigid body shows zero deformation in the loading condition, so the value of the strain is zero, and due to this the values of modulus of elasticity (elastic constant) becomes infinity because strain relates inversely with the elastic constant.

Therefore, option (B) is correct that is Y=B=n=infinity


Note: The Hook’s use the elastic constant to relate the stress and strain occurred in the body. The elastic constant related directly with the stress and inversely with the strain.