Engineering Mechanics – Section 3

1. If the masses of both the bodies, as shown in the below figure, are doubled, then the acceleration in the string will be

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A. same
B. half
C. double

Correct Answer: A. same

2. The loss of kinetic energy during inelastic impact is given by(where m1 = Mass of the first body,m2 = Mass of the second body, and u1 and u2 = Velocities of the first and second bodies respectively.)

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Correct Answer: Option A

3. The centre of gravity of a hemisphere lies at a distance of 3r / 8 from its base measured along the vertical radius.

A. Correct
B. Incorrect

Correct Answer: A. Correct

4.

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The above figure shows the three coplanar forces PQ and R acting at a point O. If these forces are in equilibrium, then

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Correct Answer: Option B

5. Moment of inertia of a rectangular section having width (b) and depth (d) about an axis passing through its C.G. and parallel to the depth (d), is

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Correct Answer: Option A

6. The polygon law of forces states that if a number of forces, acting simultaneously on a particle, be represented in magnitude and direction by the sides a polygon taken in order, then their resultant is represented in magnitude and direction by the closing side of the polygon, taken in opposite direction.

A. Correct
B. Incorrect

Correct Answer: A. Correct

7. A smooth cylinder lying on a __________ is in neutral equilibrium.

A. curved surface
B. convex surface
C. horizontal surface

Correct Answer: C. horizontal surface

8. The velocity of a particle (v) moving with simple harmonic motion, at any instant is given by(where r = Amplitude of motion, and y = Displacement of the particle from mean position.)

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Correct Answer: Option B

9. Varingon’s theorem of moments states that if a number of coplanar forces acting on a particle are in equilibrium, then

A. their algebraic sum is zero
B. their lines of action are at equal distances
C. the algebraic sum of their moments about any point in their plane is zero
D. the algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point.

Correct Answer: D. the algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point.

10. A block of mass 20 kg lying on a rough horizontal plane is connected by a light string passing over a smooth pulley to another mass 5 kg, which can move freely in the Vertical direction, as shown in the below figure. The tension in the string will __________ with the increase in the coefficient of friction.

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A. increase
B. decrease
C. not be affected

Correct Answer: A. increase

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