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 needs 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

The question was asked during an internship interview.

My question is from Work in chapter Principle of Virtual Work of Engineering Mechanics

Answer 1

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

Easiest 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.