The C.G. of a solid hemisphere lies on the central radius 3r
At distance from the plane base 3r
At distance from the plane base 3r
At distance from the plane base 3r
At distance from the plane base
Correct Answer :
D. At distance from the plane base
Related Questions
The centre of gravity of a right circular solid cone is at a distance of __________ from its base, measured along the vertical axis. (where h = Height of a right circular solid cone.)
h/2
h/3
h/4
h/6
In ideal machines, mechanical advantage is __________ velocity ratio.
Equal to
Less than
Greater than
None of these
A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if
The floor is smooth, the wall is rough
The floor is rough, the wall is smooth
The floor and wall both are smooth surfaces
The floor and wall both are rough surfaces
A framed structure, as shown in the below figure, is a 
Perfect frame
Deficient frame
Redundant frame
None of the above
The resultant of the two forces P and Q is R. If Q is doubled, the new resultant is perpendicular to P. Then
P = Q
Q = R
Q = 2R
None of these
Coefficient of friction is the
Angle between normal reaction and the resultant of normal reaction and the limiting friction
Ratio of limiting friction and normal reaction
The friction force acting when the body is just about to move
The friction force acting when the body is in motion
According to parallel axis theorem, the moment of inertia of a section about an axis parallel to the axis through centre of gravity (i.e. IP) is given by(where, A = Area of the section, IG = Moment of inertia of the section about an axis passing through its C.G., and h = Distance between C.G. and the parallel axis.)
IP = IG + Ah2
IP = IG - Ah2
IP = IG / Ah2
IP = Ah2 / IG
The forces which do not meet at one point and their lines of action do not lie on the same plane are known as
Coplanar concurrent forces
Coplanar non-concurrent forces
Non-coplanar concurrent forces
None of these
According to Lamis theorem
The three forces must be equal
The three forces must be at 120° to each other
The three forces must be in equilibrium
If 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
The unit of force in S.I. system of units is
Dyne
Kilogram
Newton
Watt
A machine having an efficiency less than 50%, is known as
Reversible machine
Non-reversible machine
Neither reversible nor non-reversible machine
Ideal machine
A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to
25
50
100
250
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.)
2π. √(g/δ)
1/2π. √(g/δ)
2π. √(δ/g)
1/2π. √(δ/g)
Which of the following is not the unit of energy?
kg m
kcal
Watt
Watt hours
The periodic time (T) is given by (where, ω = Angular velocity of particle in rad/s.)
ω/2π
2π/ω
2π × ω
π/ω
The unit of angular velocity is
m/min
rad/s
Revolutions/min
Both (B) and (C)
The length of a second's pendulum is
94.9 cm
99.4 cm
100 cm
101 cm
The moment of inertia of a square of side (a) about an axis through its centre of gravity is
a4/4
a4/8
a4/12
a4/36
Two forces are acting at an angle of 120°. The bigger force is 40 N and the resultant is perpendicular to the smaller one. The smaller force is
20 N
40 N
120 N
None of these
The rate of change of displacement of a body is called
Velocity
Acceleration
Momentum
None of these
The range of a projectile is maximum, when the angle of projection is
30°
45°
60°
90°
In a framed structure, as shown in the below figure, the force in the member BC is 
W/√3 (compression)
W/√3 (tension)
2W/√3 (compression)
2W/√3 (tension)
In order to double the period of simple pendulum, the length of the string should be
Halved
Doubled
Quadrupled
None of these
A body of weight W is required to move up on rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by (where μ = tanφ = Coefficient of friction between the plane and the body.)
P = W tanα
P = W tan (α + φ)
P = W (sinα + μcosα)
P = W (cosα + μsinα)
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
Forces are called concurrent when their lines of action meet in
One point
Two points
Plane
Perpendicular planes
The velocity ratio for the first system of pulleys is (where n is the number of pulleys.)
n
n²
2n
2n - 1
The skidding away of the vehicle on a level circular path can be avoided if the force of friction between the wheels and the ground is __________ the centrifugal force.
Less than
Greater than
Equal to
None of these
In actual 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
The moment of the force P about O as shown in the below figure is 
P × OA
P × OB
P × OC
P × AC