ME2201 Engineering Mechanics Unit 2

1. UNIT II
EQUILIBRIUM
OF
RIGID PARTICLES
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ENGINEERING MECHANICS
Mr.B.K.Parrthipan, M.E., M.B.A., (Ph.D).,
Assistant Professor / Mechatronics Engineering,
Kamaraj College of Engineering and Technology.

2. Free Body Diagram
Space Diagram:
A sketch showing the physical
conditions of the problem.
Free-Body Diagram:
A sketch showing only the forces on
the selected particle.
Free Body Diagram (FBD) is a diagram which represents all the applied forces and
moments, and reactions, which are acting on the body(ies).
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3. Free Body Diagram
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4. Types of Support
Types of Support
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5. 1. Concentrated load (or) Point load
(i) Vertical (ii) Horizontal (iii) Inclined
P
P
P
Vertical Horizontal
Inclined
Types of Loads
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6. W=wxL
2. Uniformly Distributed load (UDL)
L/ 2 L/ 2
w/ m
L
Types of Loads
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7. 3. Gradually (or) Uniformly Increasing Load (GIL)
w/ m
W=(½)bh= (½)wL
L-(L/ 3) L/ 3
L
Types of Loads
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8. 4. Gradually (or) Uniformly Decreasing Load (GDL)
w/ m
(L/ 3) L-(L/ 3)
W=(½)bh= (½)wL
L
Types of Loads
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9. Combination of UDL & GIL (OR) UDL & GDL
w1/m
w2/m
w1/ m
(w1-w2)/ m
L
W1=(w1xL)
(L/ 2)
(L/ 2)
W2=((w1-w2)xL)
(L/ 3)
L-(L/3)=2L/3
Types of Loads
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10. A structural member designed to support loads applied at
various points along the member is known as a beam.
Beam and its types
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11. Stable Equilibrium
Whenever a system gets disturbed from its position of equilibrium,
the forces acting on the system tend to bring it back to its original
position wherethe potential energyisminimum.
Ball placed on a convex surface, which has maximum potential
energy. When the ball is disturbed from its present position, it will
movefarther awayandwill nevercomebackto its originalposition.
Ball is in straight horizontal surface, which has constant potential
energy. When it is disturbed from its present position, the forces
will not tend to move the system either way and it is the
condition for neutralequilibrium.
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12. Moment of a force about an axis is the ability of the force to rotate a body about the
sameaxisin additionto the effect of the force on the body.
The moment of a force, also known asthe torque (T)is defined asthe force (F) acting at a
perpendicular distance(d).
It is vectorquantity.
➢Clock wise moment
➢Anti clock wise moment (Counter clock wise moment)
Moment
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13. When an object is in equilibrium the sum of the anticlockwise moments
about a turningpoint mustbeequalto the sumof the clockwise moments.”
sumof anticlockwisemoments =sumclockwisemoments
Principle of Moment
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14. • Apair of equal parallel unlike non collinear forcesactingonarigid bodyconstitutes a
couple.
• It is avectorquantity.
Couple
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15. Difference between Moment and Couple
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16. Varignon’s theorem
Sum of the moments of all the forces (F1, F2, & F3) - about a
point ‘O’ = Moment of their resultant force (‘R’) about the
same point.
F1d1 + F2d2 +F3d3 = R.d
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