Printed Pages:4 Paper Code: EME-101
B. Tech –1st Year (SEM.I)
Pre University Examination, May2012
– 13
Engg.Mechanics
Time: 3hrs Total
Marks: 100
Note: (1) Attempt
all questions.
(2) Be
precise in your answer.
Section-A
Tick the appropriate
answer:
1. Three forces
P, 2P and 3P are exerted along the directions of three sides of equilateral
triangle. Their Resultant is
a) √3P b) 3√3P c) 3P d) none of the above
2. If two forces
P and Q act at an angle Ө, the resultant of these two forces would make an
angle α with P such that
a) tan α = Q Sin Ө / P-Q Sin Ө b)
tan α = P Sin Ө / P+ Q Sin Ө
c) tan α = Q Sin Ө / P+ Q Cos Ө
d)
tan α= P Sin Ө / Q - P Cos Ө
3. The center of
gravity of a semicircle of radius r made
of metal is
a) on the base b)
on the perimeter
c) 3r/8 above the base d) 4r/3π above the base.
4. The parallel
axis theorem for moment of inertia is
a) Izz = Ixx + Iyy b)
IGx= Ixx + AY2
c) IGx= Ixx - AY2 d) IGx= Ixx + AX2
Fill in the blanks:
5. A body is on
the point of sliding down an inclined plane under its own weight. If the
inclination of the plane to the horizontal is 30° degree the angle of friction
will be----------------------.
6. The velocity
of a particle falling from a height h just
before touching ground is ---------------
7. A beam is
having more than two supports is called----------------------
beam and such beams are statically -----------------.
8. A car moving
with uniform acceleration covers 450m in a 5 seconds and covers 700m in the
next 5 seconds interval. The acceleration of the car is……………. .m /s2.
9. Varignon’s
theorem is related to……………
10. A truss is said to be rigid in nature when there is no --------------- on application of any
external --------------------. (2x
10=20)
Section-B
Attempt
any two parts from each question.
(3x10 = 30)
Q.1. (a)
Define parallelogram law of forces and lami’s theorem.
(b) Find the resultant of the force system given in figure-2, Also
find its position:
(c) A uniform ladder weighting 200 N and
length 6m is placed against a vertical wall in a position where its inclination
to the vertical is 30 degree. A man weighting 600N climbs the ladder. At what
position will he induce slipping? Take coefficient of friction μ = 0.2 at both the
contact surfaces of ladder.
Q.2(a) How are
the trusses classified? What are the assumptions taken while analyzing a plane truss?
(b) Draw the reactions for the beam AB
loaded through the attached strut.
Q.3. (a) Define Parallel
axis theorem and Perpendicular axis theorem.
(b) Find the Moment of Inertia of the I section
shown in figure-5 about x-x and y-y axes.
(c) Derive an
expression for mass moment of inertia of a right circular cone of base radius R, height H and mass M about its axis.
Section-C
(5x10=50)
Q.1. (a)
Define impulse. State and explain the D'Alemberts principle.
(b) The equation of motion of a particle moving in a straight line
is given by the equation s =16t +4t2-3t3
where s is the total distance covered from the starting point in meter at the end of t seconds. Find
(i) Displacement, velocity and acceleration 2 seconds after the
start
(ii) the displacement and acceleration when velocity is zero
(iii) the maximum velocity of the particle.
(c) Define the following terms: i) inertial force (ii) angle of repose (iii) coplanar non concurrent force system (iv) angular momentum
Q.2(a) A car
moving with an constant acceleration from rest in the first 50 sec, then in the
next 40 second it moves with a constant velocity, in the next 20 second it comes to rest. Find
the maximum and average velocity and the acceleration of the car:
(b)
