The centre of gravity of a semi-circle lies at a distance of __________ from its base measured along the vertical radius.
3r/ 8
4r/ 3π
8r/3
3r/4π
Correct Answer :
B. 4r/ 3π
Related Questions
If the body falls freely under gravity, then the gravitational acceleration is taken as
+8.9 m/s2
-8.9 m/s2
+9.8 m/s2
-9.8 m/s2
Two blocks A and B of masses 150 kg and 50 kg respectively are connected by means of a string as shown in the below figure. The tension in all the three strings __________ be same. 
Will
Will not
Either A or B
None of these
If three forces acting in different planes can be represented by a triangle, these will be in
Non-equilibrium
Partial equilibrium
Full equilibrium
Unpredictable
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 friction experienced by a body, when in motion, is known as
Rolling friction
Dynamic friction
Limiting friction
Static friction
Which of the following are vector quantities?
Angular displacement
Angular velocity
Angular acceleration
All of these
A pendulum which executes one beat per second is known as
Simple pendulum
Compound pendulum
Torsional pendulum
Second's pendulum
A force while acting on a body may
Change its motion
Balance the forces, already acting on it
Give rise to the internal stresses in it
All of these
The force induced in the string AB due to the load W, as shown in the below figure is 
W sinθ
W cosθ
W secθ
W cosecθ
In a screw jack, the effort required to lift the load is given by (where W = Load lifted, α = Helix angle, and φ = Angle of friction.)
P = W tan (α - φ)
P = W tan (α + φ)
P = W tan (φ - α)
P = W cos (α + φ)
Which of the following is the locus of a point that moves in such a manner that its distance from a fixed point is equal to its distance from a fixed line multiplied by a constant greater than one
Ellipse
Hyperbola
Parabola
Circle
A force is completely defined when we specify
Magnitude
Direction
Point of application
All of the above
The length of a second's pendulum is
94.9 cm
99.4 cm
100 cm
101 cm
The C.G. of a right circular solid cone of height h lies at the following distance from the base
h/2
J/3
h/6
h/4
Joule is the unit of
Force
Work
Power
Velocity
In a single threaded worm and worm wheel, the number of teeth on the worm is 50. The diameter of the effort wheel is 100 mm and that of load drum is 50 mm. The velocity ratio is
50
100
200
400
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
Pick up wrong statement about friction force for dry surfaces. Friction force is
Proportional to normal load between the surfaces
Dependent on the materials of contact surface
Proportional to velocity of sliding
Independent of the area of contact surfaces
Non-coplanar non-concurrent forces are those forces which
Meet at one point, but their lines of action do not lie on the same plane
Do not meet at one point and their lines of action do not lie on the same plane
Do not meet at one point but their lines of action lie on the same plane
None of the above
The resultant of two forces P and Q acting at an angle θ is
√(P² + Q² + 2PQ sinθ)
√(P² + Q² + 2PQ cosθ)
√(P² + Q² - 2PQ cosθ)
√(P² + Q² - 2PQ tanθ)
The unit of force in S.I. units is
kilogram
Newton
Watt
Dyne
The range of projectile on a downward inclined plane is ________ the range on upward inclined plane for the same velocity of projection and angle of projection.
Less than
More than
Equal to
None of These
The point, through which the whole weight of the body acts, irrespective of its position, is known as
Moment of inertia
Centre of gravity
Centre of percussion
Centre of mass
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
When a body falls freely under gravitational force, it possesses __________ weight.
No
Minimum
Maximum
None of these
Which one of the following statements is not correct?
The tangent of the angle of friction is equal to coefficient of friction
The angle of repose is equal to angle of friction
The tangent of the angle of repose is equal to coefficient of friction
The sine of the angle of repose is equal to coefficient to friction
Moment of inertia is the
Second moment of force
Second moment of area
Second moment of mass
All of these
A single force and a couple acting in the same plane upon a rigid body
Balance each other
Cannot balance each other
Produce moment of a couple
Are equivalent
Which of the following is not a scalar quantity?
Mass
Volume
Density
Acceleration
In the equation of virtual work, following force is neglected
Reaction of any smooth surface with which the body is in contact
Reaction of a rough surface of a body which rolls on it without slipping
Reaction at a point or an axis, fixed in space, around which a body is constrained to turn
All of the above