Engineering Mechanics Previous Year Short Question
1. What is the SI unit of force?
A. Joule
B. Newton
C. Pascal
D. Watt
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Answer: B. NewtonExplanation: Force is measured in Newton (N).
2. An ideal machine is one whose efficiency is
A. 50%
B. <50%
C. >50%
D. 100%
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Answer: D. 100%Explanation: In ideal machine there is no loss of energy or no frictional loss. It converts the total input energy into output. (N).
3. The magnitude of frictional force depends upon
A. area
B. shape
C. nature of the contact surface
D. none of the above
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Answer: C. 100%Explanation: Frictional force depends on the nature of the contact surface. Frictional force F= μR. So the magnitude of frictional force depends on co efficient of friction (μ) which refresents the nature of the surface.
4. Moment of a force
A. varies directly with its distance from the pivot
B. varies inversely with its distance from the pivot
C. is independent of its distance from the pivot
D. none of the above
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Answer: A. varies directly with its distance from the pivotExplanation: The moment of a force (also called torque) is the turning effect produced by a force about a point or axis.It is calculated as: Moment =.Force x Perpendicular distance from the pivot.
Therefor for is direcly proportional with distance from pivot.
5. Lami’s theorem is applicable to
A.coplaner forces
B. concurrent forces
C. coplaner and concurrent forces
D. like parallel forces
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Answer: C. coplaner and concurrent forcesExplanation:
6. The resultant in parallelogram law of forces has maximum value when the angle between two forces is equal to
A. 30°
B. 90°
C. 0°
D. 180°
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Answer: C. 0°Explanation:
7. A force of 100 N is acting at an angle of 60° with the horizontal. What is the vertical component of the force
A. 50 N
B. 86.6 N
C. 100 N
D. 43.3 N
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Answer: B. 86.6 NExplanation:
8. Axis passing through the centroid is known as
A. Parallel axis
B. Perpendicular axis
C. Centroidal axis
D. None of these
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Answer: C. Centroidal axisExplanation:
9. Co-efficient of friction is the ratio of
A. Normal reaction to limiting friction
B. Limiting friction to the weight of the body to be moved
C. Limiting friction to normal reaction
D. None of the above
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Answer: C. Limiting friction to normal reactionExplanation:
10. The velocity ratio of a wheel and axle with ‘D’ and ‘d’ as the diametres of effort wheel and load axle, is
A. D + d
B. D – d
C. Dxd
D. D/d
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Answer: D. D/dExplanation:
11. In a simple lifting machine, the following parameter remains constant
A. Efficiency
B. velocity ratio
C. mechanical advantage
D. All of these
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Answer: B. velocity ratioExplanation:
12. In simple lifting machine, Load vs. Effort graph is
A. Straight-line
B. Parabolic curve
C. Hyperbolic curve
D. none of these
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Answer: A. Straight-lineExplanation:
13. According to the Principle of Transmissibility of Force, the effect of a force on a rigid body remains unchanged if
A. the force is removed from the body
B. the force is applied to a different body
C. the force is shifted along its line of action
D. the force is doubled.
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Answer: C. the force is shifted along its line of actionExplanation:
14. Which of the following is NOT a condition for the equilibrium of a co-planar system of non-concurrent parallel forces?
A. Sum of all horizontal forces must be zero
B. Sum of all vertical forces must be zero
C. Sum of all moments about any point must be zero
D. The forces must always be equal in magnitude.
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Answer: D. The forces must always be equal in magnitude.Explanation:
15. A block resting on a rough plane having angle of friction 12° will impend motion, if the inclination of the surface with the horizontal is
A. 11°
B. 12°
C. 13°
D. 15°
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Answer: B. 12°Explanation:
16. A machine has a power rating of 500 W. How much work does it do in 30 seconds?
A. 1500 J
B. 15 kJ
C. 150 kJ
D. 10 kJ
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Answer: B. 15 kJExplanation:
17.
A.
B.
C.
D.
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Answer: C.Explanation:
18.
A.
B.
C.
D.
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Answer: C.Explanation:
19.
A.
B.
C.
D.
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Answer: C.Explanation:
20.
A.
B.
C.
D.
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Answer: C.Explanation: