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.

Which of the following statements of D’Alembert’s principle are co

1.	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.
A.	1 and 3 only
B.	1 and 2 only
C.	2 and 3 only
D.	1, 2 and 3
Answer» C. 2 and 3 only