Regulation : 10
Code No: CE102
VIGNAN UNIVERSITY :: VADLAMUDI - 522 213
Vignan’s Foundation for Science, Technology and Research (Estd. U/s 3 of UGC Act of 1956)
I B.Tech I Semester Regular Examination, December, 2011
ENGINEERING MECHANICS
(BT / CIVIL / ECE / EEE)
Time: 3 hours
Max. Marks : 60
Answer ONE question from each unit
All Questions carry equal marks
***
UNIT – I
1.
a) State and explain the parallelogram law of forces.
[4M]
b) Find the resultant force and point of action of resultant force for the force systems
shown in Figure1. Show the resultant force on the figure.
[8M]
Fig.1
(OR)
2.
a) State and prove theorem of Varignon.
[4M]
b) Two forces P and 2P act on a particle. If the first force is increased by 12N and
second force is doubled, the direction of their resultant remains unchanged. Find the
value of P.
[8M]
UNIT – II
3.
Determine the magnitude and direction of the smallest force P required to start the
wheel over the block as shown in Figure2.The self-weight of the wheel is 10kN and
radius is 0.6m.
[12M]
Fig.2
(OR)
4.
a) What is free body diagram, explain with examples.
1 of 3
[4M]
Regulation : 10
Code No: CE102
b) A roller weighing 2000 N rests on an inclined bar weighing 800N as shown in Figure
3. Assuming weight of bar AB is negligible, determine the reactions developed at
supports C and D.
[8M]
Fig. 3
UNIT – III
5.
6.
a) State and prove parallel axis theorem and perpendicular axis theorem.
[4M]
b) Determine the moment of inertia of the shaded area as shown in Figure 4 about AB
and about its centroidal axis parallel to AB.
[8M]
Fig. 4
(OR)
a) Define the centroid and derive the centroidal coordinates for triangular cross
sectional area.
[4M]
b) Find the moment of inertia of the shaded part of the figure shown in Figure 5 with
respect to the centroidal axis.
[8M]
Fig.5
UNIT – IV
7.
a) What are the laws of friction.
[4M]
b) What is the value of P in the system shown to cause the motion to impend? Assume
the pulley is smooth and coefficient of friction between the other contact surfaces is 0.2[8M]
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Regulation : 10
Code No: CE102
Fig.6
8.
(OR)
a) Define angle of friction and angle of repose.
[4M]
b) In figure 7, the coefficient of friction between the rope and the fixed drum is 0.2 and
between the other surfaces of contact is 0.3. Determine the minimum weight W to
prevent downward motion of the 1000 N block.
[8M]
Fig.7
UNIT – V
9.
a) State the principle of impulse – momentum and conservation of momentum.
[4M]
0
0
b) Two rough planes inclined at 30 and 60 to the horizontal are placed back to back as
shown in Figure 8. The blocks of weights 50N and 100N are placed on the faces and
are connected by a string running parallel to planes and passing over a frictionless
pulley. If the coefficient of friction between planes and blocks is 0.3, find the resulting
acceleration and tension in the string.
[8M]
Fig.8
(OR)
10.
a) State work energy theorem.
[4M]
b) A small steel ball is shot vertically upwards from the top of a building 25 m above
the ground with an initial velocity of 18 m/sec i) in what time it will reach maximum
height
ii) how high above the building will the
ball rise?
[8M]
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