Moment of inertia of a hollow rectangular section as shown in the below figure about X-X axis, is 
(BD³/12) - (bd³/12)
(DB³/12) - (db³/12)
(BD³/36) - (bd³/36)
(DB³/36) - (db³/36)
Correct Answer :
A. (BD³/12) - (bd³/12)
Related Questions
The velocity of a body on reaching the ground from a height h, is
2.√(gh)
√(gh)
√(2gh)
2g.√h
The centre of gravity a T-section 100 mm × 150 mm × 50 mm from its bottom is
50 mm
75 mm
87.5 mm
125 mm
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 width (b), is
db³/12
bd³/12
db³/36
bd³/36
If a number of coplanar forces acting at a point be in equilibrium, the sum of clockwise moments must be __________ the sum of anticlockwise moments, about any point.
Equal to
Less than
Greater than
None of these
Centre of gravity of a thin hollow cone lies on the axis at a height of
One-fourth of the total height above base
One-third of the total height above base
One-half of the total height above base
Three-eighth of the total height above the base
For a self locking machine, the efficiency must be
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Less than 50 %
Greater than 50 %
100 %
The coefficient of friction depends upon
Nature of surfaces
Area of contact
Shape of the surfaces
All of the above
A single force and a couple acting in the same plane upon a rigid body
Balance each other
Cannot balance each other
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Are equivalent
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.
Equal to
Less than
Greater than
None of these
In order to double the period of simple pendulum, the length of the string should be
Halved
Doubled
Quadrupled
None of these
In a framed structure, as shown in the below figure, the forces in the members AB and BC are respectively 
√3. W (tensile) and 2W (compressive)
2W (tensile) and √3. W (compressive)
2√3. W (tensile) and 2√3. W (compressive)
None of the above
The weight of a body is due to
Gravitational pull exerted by the earth
Forces experienced by body in atmosphere
Force of attraction experienced by particles
Gravitational force of attraction towards the centre of the earth
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
Principle of independence of forces
Principle of resolution of forces
Principle of transmissibility of forces
None of these
The linear acceleration (a) of a body rotating along a circular path of radius (r) with an angular acceleration of α rad/s2, is
a = α/ r
a = α.r
a = r / α
None of these
Which of the following are vector quantities?
Linear displacement
Linear velocity
Linear acceleration
All of these
When a rigid body is suspended vertically, and it oscillates with a small amplitude under the action of the force of gravity, the body is known as
Simple pendulum
Compound pendulum
Torsional pendulum
Second's pendulum
The maximum frictional force which comes into play when a body just begins to slide over another surface is called
Limiting friction
Sliding friction
Rolling friction
Kinematic friction
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Magnitude
Direction
Position or line of action
All of the above
D' Alembert's principle is used for
Reducing the problem of kinetics to equivalent statics problem
Determining stresses in the truss
Stability of floating bodies
Designing safe structures
If three forces acting in one plane upon a rigid body, keep it in equilibrium, then they must either
Meet in a point
Be all parallel
At least two of them must meet
All the above are correct
Work done is said to be zero, when
Some force acts on a body, but displacement is zero
No force acts on a body but some displacement takes place
Either (A) or (B)
None of the above
A semicircular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi circular disc and horizontal surface is μ. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will
Remain horizontal
Slant up towards direction of pull
Slant down towards direction of pull
None of the above
In ideal machines
Mechanical advantage is greater than velocity ratio
Mechanical advantage is equal to velocity ratio
Mechanical advantage is less than velocity ratio
Mechanical advantage is unity
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Meet
Do not meet
Either A or B
None of these
If the masses of both the bodies, as shown in the below figure, are doubled, then the acceleration in the string will be 
Same
Half
Double
None of these
According to law of triangle of forces
Three forces acting at a point will be in equilibrium
Three forces acting at a point can be represented by a triangle, each side being proportional to force
If three forces acting upon a particle are represented in magnitude and direction by the sides of a triangle, taken in order, they will be in equilibrium
If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two
In a framed structure, as shown in the below figure, the force in the member AB is __________ the force in member AC. 
Half
Equal to
Double
None of these
The acceleration of a particle moving with simple harmonic motion is __________ at the mean position.
Zero
Minimum
Maximum
None of these
If the masses of both the bodies, as shown in the below figure, are reduced to 50 percent, then tension in the string will be 
Same
Half
Double
None of these
The velocity ratio of a simple wheel and axle with D and d as the diameters of effort wheel and load axle, is
D + d
D - d
D × d
D / d