If n = number of members and y = number of joints, then for a perfect frame, n = ?
1/2
2/3
3/2
2/4
Correct Answer :
B. 2/3
Related Questions
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
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
A spherical body is symmetrical about its perpendicular axis. According to Routh's rule, the moment of inertia of a body about an axis passing through its centre of gravity is (where, M = Mass of the body, and S = Sum of the squares of the two semi-axes.)
MS/3
MS/4
MS/5
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
The maximum mechanical advantage of a lifting machine is
1 + m
1 - m
1 / m
m
The efficiency of a lifting machine is the ratio of
Output to the input
Work done by the machine to the work done on the machine
Mechanical advantage to the velocity ratio
All of the above
The moment of a force
Is the turning effect produced by a force, on the body, on which it acts
Is equal to the product of force acting on the body and the perpendicular distance of a point and the line of action of the force
Is equal to twice the area of the triangle, whose base is the line representing the force and whose vertex is the point, about which the moment is taken
All of the above
The centre of percussion of a solid cylinder of radius r resting on a horizontal plane will be
r/2
2r/3
r/A
3r/2
The centre of percussion of the homogeneous rod of length L suspended at the top will be
L/2
L/3
3L/4
2L/3
The force induced in the string BC due to the load W as shown in the below figure is 
W sinθ
W cosθ
W tanθ
W cotθ
A ladder is resting on a smooth ground and leaning against a rough vertical wall. The force of friction will act
Towards the wall at its upper end
Away from the wall at its upper end
Downward at its upper end
Upward at its upper end
The maximum efficiency of a lifting machine is
1/m
V.R./m
m/V.R.
1/(m × V.R.)
The forces which meet at one point, but their lines of action __________ on the same plane, are Known as non-coplanar concurrent forces.
Lie
Do not lie
Either A or B
None of these
When the spring of a watch is wound, it will possess
Strain energy
Kinetic energy
Heat energy
Electrical energy
The time of flight of a projectile on downward inclined plane depends upon
Angle of projection
Angle of inclination of the plane
Both (A) and (B)
None of these
A block of mass 20 kg lying on a rough horizontal plane is connected by a light string passing over a smooth pulley to another mass 5 kg, which can move freely in the Vertical direction, as shown in the below figure. The tension in the string will __________ with the increase in coefficient of friction. 
Increase
Decrease
Not be effected
None of these
The principle of transmissibility of forces states that, when a force acts upon a body, its effect is
Same at every point on its line of action
Different at different points on its line of action
Minimum, if it acts at the centre of gravity of the body
Maximum, if it acts at the centre of gravity of the body
The coefficient of friction depends upon
Nature of surfaces
Area of contact
Shape of the surfaces
All of the above
Angle 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 ratio of minimum friction force to the friction force acting when the body is just about to move
The ratio of minimum friction force to friction force acting when the body is in motion
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
Coplanar 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
Meet at one point and their lines of action also lie on the same plane
Do not meet at one point, but their lines of action lie on the same plane
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)
Which of the following is a vector quantity?
Energy
Mass
Momentum
Angle
A smooth cylinder lying on its convex surface remains in __________ equilibrium.
Stable
Unstable
Neutral
None of these
The unit of angular velocity is
m/min
rad/s
Revolutions/min
Both (B) and (C)
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
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 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
The unit of force in S.I. system of units is
Dyne
Kilogram
Newton
Watt
The necessary condition for forces to be in equilibrium is that these should be
Coplanar
Meet at one point
Both (A) and (B) above
All be equal