Sunday 5 December 2010

SOLUTION OF PRESEMESTER EXAMINATION: ENGINEERING MECHANICS

SOLUTION OF PRESEMESTER EXAMINATION:
ENGINEERING MECHANICS

©subhankar_karmakar

GROUP-A

Q.1 Answer the following questions as per the instructions 2x20=20

Choose the correct answer of the following questions:

(i) A truss hinged at one end, supported on rollers at the other, is subjected to horizontals load only. Its reaction at the hinged end will be

(a) Horizontal;                   (b) Vertical
(c) Both horizontal & vertical
(d) None of the above.

Ans: (c) both horizontal & vertical


(ii) The moment of inertia of a circular section of diameter D about its centroidal axis is given by the expression

(a) π(D)4/16           (b) π(D)4/32
(c) π(D)4/64           (d) π(D)4/4

Ans: (c) π(D)4/64


Fill in the blanks in the following questions:


(iii)The distance of the centroid of an equilateral triangle with each side(a) is …………. from any of the three sides.

Ans a /(2√3)


(iv)Poisson’s ratio is defined as the ratio between ……. and ………… .

Ans: Lateral Strain, Longitudinal Strain


(v)If two forces of equal magnitudes P having an angle 2Ө between them, then their resultant force will be equal to ________ .

Ans: 2P CosӨ


Choose the correct word/s.

(vi) Two equal and opposite force acting at different points of a rigid body is termed as (Bending Moment/ Torque/ Couple).

Ans: Couple







Choose correct answer for the following parts:


(vii) Statement 1:

In stress strain graph of a ductile material, yield point starts at the end of the elastic limit.

Statement 2:

At yielding point, the deformation becomes plastic by nature.

(a) Statement 1 is true, Statement 2 is true.
(b) Statement 1 is true, Statement 2 is true and they are unrelated with each other
(c) Statement 1 is true, statement 2 is false.
(d) Statement 1 is false, Statement 2 is false.

Ans: (a) Statement 1 is true, Statement 2 is true.


(viii) Statement 1:

It is easier to pull a body on a rough surface than to push the body on the same surface.

Statement 2:

Frictional force always depends upon the magnitude of the normal force.

(a) Statement 1 is true, Statement 2 is true.
(b) Statement 1 is true, Statement 2 is true and they are unrelated
(c) Statement 1 is true, statement 2 is false.
(d) Statement 1 is false, Statement 2 is false.

Ans: (a) Statement 1 is true, Statement 2 is true.


(ix) In a cantilever bending moment is maximum at

(a) free end            (b) fixed end
(c) at the mid span (d) none of these

Ans: (b) fixed end


(x) The relationship between linear velocity and angular velocity of a cycle

(a) exists under all conditions
(b) does not exist under all conditions
(c) exists only when it moves on horizontal plane.
(d) none of these

Ans: (a) exists under all conditions
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SOLUTION OF PRESEMESTER EXAMINATION:
ENGINEERING MECHANICS PART-II

©subhankar_karmakar