Coulomb friction is the friction between
Bodies having relative motion
Two dry surfaces
Two lubricated surfaces
Solids and liquids
Correct Answer :
A. Bodies having relative motion
Related Questions
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
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)
A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t² (t - 4), the acceleration of the particle will be given by the equation
6t² - 8t
3t² + 2t
6f - 8
6f - 4
The time of flight (t) of a projectile on a horizontal plane is given by
t = 2u. sinα/g
t = 2u. cosα/g
t = 2u. tanα/g
t = 2u/g.sinα
The process of finding out the resultant force is called __________ of forces.
Composition
Resolution
Decomposition
None of these
In the lever of third order, load W, effort P and fulcrum F are oriented as follows
W between P and F
F between W and P
P between W and F
W, P and F all on one side
A smooth cylinder lying on its convex surface remains in __________ equilibrium.
Stable
Unstable
Neutral
None of these
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
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)
The velocity ratio of a differential wheel and axle with D as the diameter of effort wheel and d1 and d2 as the diameters of larger and smaller axles respectively, is
D/(d₁ + d₂)
D/(d₁ - d₂)
2D/(d₁ + d₂)
2D/(d₁ - d₂)
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
Moment of inertia of a triangular section of base (b) and height (h) about an axis passing through its C.G. and parallel to the base, is
bh3/4
bh3/8
bh3/12
bh3/36
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
Which of the following is not the unit of power?
kW (kilowatt)
hp (horse power)
kcal/sec
kcal/kg sec
On a ladder resting on smooth ground and leaning against vertical wall, the force of friction will be
Towards the wall at its upper end
Away from the wall at its upper end
Upwards at its upper end
Downwards at its upper end
A pendulum which executes one beat per second is known as
Simple pendulum
Compound pendulum
Torsional pendulum
Second's pendulum
If a number of forces act simultaneously on a particle, it is possible
Not a replace them by a single force
To replace them by a single force
To replace them by a single force through C.G.
To replace them by a couple
The energy possessed by a body, for doing work by virtue of its position, is called
Potential energy
Kinetic energy
Electrical energy
Chemical energy
Which is the correct statement about law of polygon of forces?
If any number of forces acting at a point can be represented by the sides of a polygon taken in order, then the forces are in equilibrium
If any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon, then the forces are in equilibrium
If a polygon representing forces acting at a point is closed then forces are in equilibrium
If any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon taken in order, then the forces are in equilibrium
When a body falls freely under gravitational force, it possesses __________ weight.
No
Minimum
Maximum
None of these
Which of the following statement is incorrect?
A force acting in the opposite direction to the motion of the body is called force of friction
The ratio of the limiting friction to the normal reaction is called coefficient of friction
A machine whose efficiency is 100% is known as an ideal machine
The velocity ratio of a machine is the ratio of load lifted to the effort applied
A machine having an efficiency greater than 50%, is known as
Reversible machine
Non-reversible machine
Neither reversible nor non-reversible machine
Ideal machine
If a rigid body is in equilibrium under the action of three forces, then
These forces are equal
The lines of action of these forces meet in a point
The lines of action of these forces are parallel
Both (B) and (C) above
The acceleration of a body sliding down an inclined surface is
g sinθ
g cosθ
g tanθ
None of these
Tangent of angle of friction is equal to
Kinetic friction
Limiting friction
Angle of repose
Coefficient of friction
Moment of inertia of a hollow circular section, as shown in the below figure about an axis perpendicular to the section, is __________ than that about X-X axis. 
Two times
Same
Half
None of these
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)
The friction experienced by a body, when at rest, is known as
Static friction
Dynamic friction
Limiting friction
Coefficient of friction
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
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