Question

The supports in the 3D are having more than three reaction forces. Because they are having three axis on which the components of the work done need to be zero.

(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

I have been asked this question in an international level competition.

My doubt is from Work topic in section Principle of Virtual Work of Engineering Mechanics

Answer 1

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

Best explanation: As 3D is defined as the three axis system, we have to consider the equilibrium in all the three axis. This will make the equilibrium go on all the axis of the 3D space. And hence will cancel all the forces.