Here is the free body diagram for the given figure: FBD F1 F2 F3 The free body diagram shows the particle with all the three forces F1, F2 and F3 acting on it. No other external forces are shown as only the applied forces are to be shown in a free body diagram.

1. Islamic University of Technology (IUT)
A subsidiary organ of Organization of Islamic Cooperation (OIC)
Engineering Mechanics
MCE 4103
Credit Hour: 4.00
Md. Abu Shaid Sujon
Lecturer
MCE Department
Room No: 115 (1st Academic Building)
Email: sujonmce@iut-dhaka.edu Cellphone: 01735933791

2. What is Mechanics?
Mechanics is a branch of physics, since it deals
with physical phenomena. Mechanics describes
and predicts the state of rest or motion of
bodies under the action of forces.
Concerned with the state of rest of motion of
bodies that are subjected to the action if forces.

3. Branches of Mechanics
Mechanics
Rigid Body
Mechanics
Statics
Dynamics
Deformable
body mechanics
Fluid Mechanics
Compressible
Incompressible

4. Rigid Body
• No deformation under any load
Rigid body mechanics :: Idealization
• –A combination of large number of particles in which all
particles remain at a fixed distance(practically) from one
another before and after applying a load
• –Material properties not required when analyzing the
forces acting on the body
• –design and analysis of many types of structural
members, mechanical components, electrical devices,
etc., encountered in engineering.

5. Rigid body mechanics :: Statics
• Statics–equilibrium of rigid body under
action of forces

6. Rigid body mechanics :: Dynamics
• Dynamics–motion of bodies
(acceleration/deceleration)

7. Mechanics: Fundamental Concepts
• Length(Space)
• –Position of a point in space
– Coordinate system
• –Cartesian(x, y, z)
• –Spherical(r, θ, Φ)
• –Cylindrical(ρ, Φ, z)
• –Describe size of the physical system
– Dimensions
• –Distance, geometric properties
• –Basic quantity/dimension

8. Mechanics: Spherical coordinate
system
• Application–Separation of variables in partial
differential equations, e.g., Laplace eqn.

9. Mechanics: Cylindrical coordinate
system
• Application–Physical phenomena with
spherical symmetry, e.g., water flow in a
circular pipe

10. Mechanics: Fundamental Concepts
• Time
– –Measure of succession of events
– –Basic quantity/dimension
 Mass
– –Quantity of matter in a body
– –Measure of inertia–Basic quantity/dimension

11. Mechanics: Fundamental Concepts

12. Mechanics: Fundamental Concepts

13. Mechanics: Newton’s Three Laws of
Motion

14. Mechanics: Newton’s Three Laws of
Motion

15. Mechanics: Newton’s Three Laws of
Motion

16. Mechanics: Newton’s Law of
Gravitational Attraction

17. Mechanics : Gravitational Attraction of
Earth

18. Mechanics: Units

19. Mechanics: Prefixes of units

20. Mechanics: Accuracy

21. Chapter 3
Equilibrium of a Particle
• A particle is said to be in equilibrium if it remains at
rest if originally at rest, or has a constant velocity if
originally in motion.
• Most often, however, the term “equilibrium” or, more
specifically, “static equilibrium” is used to describe an
object at rest.
• To maintain equilibrium, it is necessary to satisfy
Newton’s first law of motion, which requires the
resultant force acting on a particle to be equal to zero .
This condition may be stated mathematically as

22. Free Body Diagram
A drawing that shows the particle with all the
forces that act on it is called a free body
diagram.

24. Draw The FBD diagram for the
following figure

25. Draw The FBD diagram for the
following figure

26. Draw The FBD diagram for the
following figure

27. Draw The FBD diagram for the
following figure

28. Draw The FBD diagram for the
following figure