Which of the following statements of D’Alembert’s principle are correct?
1. The net external force F actually acting on the body and the inertia force F1 together keep the body in a state of fictitious equilibrium.
2. The equation of motion may be written as F + (-ma) = 0 and the fictitious force (-ma) is called an inertia force.
3. It tends to give solution of a static problem an appearance akin to that of a dynamic problem.1
1 and 3 only
2
1 and 2 only
3
2 and 3 only
4
1, 2 and 3