This document contains information about Devaprakasam D, a professor of mechanical engineering at VIT. It includes his contact information, the engineering mechanics course he teaches, and slides on topics like wedges, friction, and ladders. The slides provide equations, diagrams, and example problems related to these mechanics topics.

1. DEVAPRAKASAM DEIVASAGAYAM
Professor of Mechanical Engineering
Room:11, LW, 2nd Floor
School of Mechanical and Building Sciences
Email: devaprakasam.d@vit.ac.in, dr.devaprakasam@gmail.com
MEE1002: Engineering Mechanics (2:1:0:0:3)
Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933

2. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Wedges are simple machines used
to raise large stone blocks and
other heavy loads. These loads can
be raised by applying to the wedge
a force usually considerably
smaller than the weight of the load.
In addition, because of the friction
between the surfaces in contact, a
properly shaped wedge will remain
in place after being forced under
the load. Wedges can thus be used
advantageously to make small
adjustments in the position of
heavy pieces of machinery.

3. Static or Dynamic?
• Static Friction
• Kinetic Friction
tanφs= Fm/N=µs N/N
tanφk=Fk/N=µk N/N
P
N
Ff
W
Ff
P
Motion
Fm
Fk

4. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

5. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

6. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

7. Static or Dynamic?
P
N
Ff
W
W
θ
θ
N
W sinθ
W cosθ
N cosθ
N sinθ
Case 1: Ff>P, (µsN>P) No Motion
Case 2: Fm=P, (µsN=P) Impending Motion
Case3: Fk<P, (µkN<P) Motion
Case 1: Ff>P, (µs N Sinθ>P) , No Motion
Case 2: Fm=P, (µs N Sinθ=P), Impending
Motion
Case3: Fk<P, (µk N Sinθ<P) Motion,
θ

8. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933

9. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

10. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

11. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

12. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction
θ
θ
y
x
F
N
Maximum Friction Force

13. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction
x
Maximum Friction Force

14. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction

15. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction
y
θ
θ
x
F
N
Maximum
Friction Force
Actual Friction Force

16. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Dry Friction
y
Maximum
Friction Force
Actual Friction Force

17. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
It is convenient to replace the normal force N and the
friction force F by their resultant R.
Applied force P has a horizontal component Px which tends to move
the block, the force R will have a horizontal component F and, thus, will
form an angle φ with the normal to the surface
If Px is increased until
motion becomes
impending, the angle
between R and the vertical
grows and reaches a
maximum value.This value
is called the angle of static
friction and is denoted by
φs .

18. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
If motion actually takes place, the magnitude of the friction
force drops to Fk; similarly, the angle f between R and N
drops to a lower value φk, called the angle of kinetic friction

19. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933

20. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933

21. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933

22. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Two 8° wedges of negligible weight are used to move and position the 800-kg
block. Knowing that the coefficient of static friction is 0.30 at all surfaces of
contact, determine the smallest force P that should be applied as shown to one of
the wedges.

23. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
WEDGES

24. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
WEDGES
W
8°
8°
16.7°
R1
R2
16.7°
16.7°
R2
R1
16.7°
24.7°
α
7848N

25. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
WEDGES
R3
R1
90°-16.7°
β
P
90°-24.7°
R3
R1
P
16.7° 24.7°

26. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
WEDGES

27. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
WEDGES
W
16.7°
R1
R2
16.7°
16.7°
R2
R1
16.7°
16.7°
α
7848N
`

28. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
WEDGES
R3
R1
90°-24.7°
β
P
90°-16.7°
R3
R1
P
16.7°
24.7°
16.7°8°

29. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Ladder

30. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Ladder
NC
FC
NA
FA
NB
FB
NB
FB
40lb 40lb

31. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Ladder
;
;
;
;
;
;
;
;
;
=0;
6
;
;
;
17.143;
;
=0;
;
;

32. Devaprakasam D, Email: devaprakasam.d@vit.ac.in, Ph: +91 9786553933
Ladder