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.

This question was previously asked in
ESE Mechanical 2020 Official Paper
View all UPSC IES Papers >
  1. 1 and 3 only
  2. 1 and 2 only
  3. 2 and 3 only
  4. 1, 2 and 3

Answer (Detailed Solution Below)

Option 2 : 1 and 2 only
Free
ST 1: UPSC ESE (IES) Civil - Building Materials
6.2 K Users
20 Questions 40 Marks 24 Mins

Detailed Solution

Download Solution PDF

Explanation:

D’Alembert’s principle involves

  1. D'Alembert's principle of virtual work states that a system of rigid bodies is in dynamic equilibrium when the virtual work of the sum of the applied forces and the inertial forces is zero for any virtual displacement of the system.

Equation of motion is given by:

F = ma

It can be rearranged as:

F+ (-ma) = 0 (As per D’Alembert’s principle)

where (-ma) is the inertia force and F is an external force.

  1. It tends to give the solution procedure of a dynamic problem an appearance akin to that of a static problem.
Latest UPSC IES Updates

Last updated on May 28, 2025

->  UPSC ESE admit card 2025 for the prelims exam has been released. 

-> The UPSC IES Prelims 2025 will be held on 8th June 2025.

-> The selection process includes a Prelims and a Mains Examination, followed by a Personality Test/Interview.

-> Candidates should attempt the UPSC IES mock tests to increase their efficiency. The UPSC IES previous year papers can be downloaded here.

More Kinematics and Kinetics Questions

Get Free Access Now
Hot Links: teen patti fun teen patti master 2024 teen patti palace teen patti refer earn teen patti master gold