Question

For the conditions of the stability of equilibrium configuration of the body, i.e. the body only the external forces defines the equilibrium. Because the internal forces cancels out so not to be considered.

(a) The first part of the statement is false and other part is true

(b) The first part of the statement is false and other part is false too

(c) The first part of the statement is true and other part is false

(d) The first part of the statement is true and other part is true too

This question was posed to me in my homework.

Enquiry is from Stability of Equilibrium Configurations topic in chapter Principle of Virtual Work of Engineering Mechanics

Answer 1

Right answer is (c) The first part of the statement is true and other part is false

Easiest explanation: The application of the internal forces does affect the conditions of the equilibrium of the body. Not only the external but the internal forces that are developed by the sake of external forces does develop a tending effect on the equilibrium of the body. Thus the internal forces doesn’t cancels out.