300 Important Engineering Mechanics MCQ Question and Answer | PDF Free Download
1.The M.I. of hollow circular section about a central axis perpendicular to section as compared to its M.I. about horizontal axis is
- ASame
- BDouble
- CHalf
- DFour times
2.Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to
- AArea of the triangle
- BTwice the area of the triangle
- CHalf the area of the triangle
- DNone of these
3.The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is known as
- APrinciple of independence of forces
- BPrinciple of resolution of forces
- CPrinciple of transmissibility of forces
- DNone of these
4.If two bodies having masses m1 and m2 (m1>m2) have equal kinetic energies, the momentum of body having mass m1 is _________ the momentum of body having mass m2.
- AEqual to
- BLess than
- CGreater than
- DNone of these
5.According to principle of moments
- AIf a system of coplanar forces is in equilibrium, then their algebraic sum is zero
- BIf a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero
- CThe algebraic sum of the moments of any two forces about any point is equal to moment of the resultant about the same point
- DPositive and negative couples can be balanced
6.According to Lami’s theorem
- AThe three forces must be equal
- BThe three forces must be at 120° to each other
- CThe three forces must be in equilibrium
- DIf the three forces acting at a point are in equilibrium, then each force is proportional to the sine of the angle between the other two
7.Mass moment of inertia of a thin rod about its one end is ___________ the mass moment of inertia of the same rod about its mid-point
- ASame as
- BTwice
- CThrice
- DFour times
8.A force while acting on a body may
- AChange its motion
- BBalance the forces, already acting on it
- CGive rise to the internal stresses in it
- DAll of these
9.The product of either force of couple with the arm of the couple is called
- AResultant couple
- BMoment of the forces
- CResulting couple
- DMoment of the couple
10.The moment of inertia of a rectangular section 3 cm wide and 4 cm deep about X-X axis is
- A9 cm4
- B12 cm4
- C16 cm4
- D20 cm4
11.A ladder is resting on a smooth ground and leaning against a rough vertical wall. The force of friction will act
- ATowards the wall at its upper end
- BAway from the wall at its upper end
- CDownward at its upper end
- DUpward at its upper end
12.A ladder is resting on a rough ground and leaning against a smooth vertical wall. The force of friction will act
- ADownward at its upper end
- BUpward at its upper end
- CZero at its upper end
- DPerpendicular to the wall at its upper end
13.A weight of 1000 N can be lifted by an effort of 80 N. If the velocity ratio is 20, the machine is
- AReversible
- BNon-reversible
- CIdeal
- DNone of these
14.In the equation of virtual work, following force is neglected
- AReaction of any smooth surface with which the body is in contact
- BReaction of a rough surface of a body which rolls on it without slipping
- CReaction at a point or an axis, fixed in space, around which a body is constrained to turn
- DAll of the above
15.A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if
- AThe floor is smooth, the wall is rough
- BThe floor is rough, the wall is smooth
- CThe floor and wall both are smooth surfaces
- DThe floor and wall both are rough surfaces
16.An ideal machine is one whose efficiency is
- ABetween 60 and 70 %
- BBetween 70 and 80%
- CBetween 80 and 90%
- D100%
17.The velocity of a body on reaching the ground from a height h, is
- A2.√(gh)
- B√(gh)
- C√(2gh)
- D2g.√h
18.The range of projectile will be maximum for a given velocity of projectile, when the angle of projection (α) is
- Aβ/2
- B30° + β/2
- C45° + β/2
- D60° + β/2
19.The moment of inertia of a sphere of mass 'm' and radius 'r', about an axis tangential to it, is
- A2mr²/3
- B2mr²/5
- C7mr²/3
- D7mr²/5
20.One end of a helical spring is fixed while the other end carries the load W which moves with simple harmonic motion. The frequency of motion is given by (where δ = Deflection of the spring.)
- A2π. √(g/δ)
- B1/2π. √(g/δ)
- C2π. √(δ/g)
- D1/2π. √(δ/g)