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
Correct Answer :
C. Slant down towards direction of pull
Related Questions
The coefficient of friction depends upon
Nature of surfaces
Area of contact
Shape of the surfaces
All of the above
A machine having an efficiency greater than 50%, is known as
Reversible machine
Non-reversible machine
Neither reversible nor non-reversible machine
Ideal machine
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
The moment of inertia of a thin rod of mass m and length l, about an axis through its centre of gravity and perpendicular to its length is
ml2/4
ml2/ 6
ml2/8
ml2/12
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
In order to double the period of simple pendulum, the length of the string should be
Halved
Doubled
Quadrupled
None of these
A rubber ball is dropped from a height of 2 m. If there is no loss of velocity after rebounding, the ball will rise to a height of
1 m
2 m
3 m
4 m
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
The velocity of a body on reaching the ground from a height h, is
2.√(gh)
√(gh)
√(2gh)
2g.√h
For a self locking machine, the efficiency must be
Equal to 50 %
Less than 50 %
Greater than 50 %
100 %
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)
The forces, which meet at one point and their lines of action also lie on the same plane, are known as
Coplanar concurrent forces
Coplanar non-concurrent forces
Non-coplanar concurrent forces
Non-coplanar non-concurrent forces
A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly
38 m
62.5 m
96 m
124 m
Moment of inertia of a triangular section of base (b) and height (h) about an axis through its base, is
bh3/4
bh3/8
bh3/12
bh3/36
If a body is acted upon by a number of coplanar non-concurrent forces, it may
Rotate about itself without moving
Move in any one direction rotating about itself
Be completely at rest
All of these
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
Three forces acting on a rigid body are represented in magnitude, direction and line of action by the three sides of a triangle taken in order. The forces are equivalent to a couple whose moment is equal to
Area of the triangle
Twice the area of the triangle
Half the area of the triangle
None of these
The time of flight (t) of a projectile on an upward inclined plane is (where u = Velocity of projection, α = Angle of projection, and β = Inclination of the plane with the horizontal.)
t = g cos β/2u sin (α - β)
t = 2u sin (α - β)/g cos β
t = g cos β/2u sin (α + β)
t = 2u sin (α + β)/g cos β
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
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
A machine having an efficiency less than 50%, is known as
Reversible machine
Non-reversible machine
Neither reversible nor non-reversible machine
Ideal machine
The possible loading in various members of framed structures are
Compression or tension
Buckling or shear
Shear or tension
All of the above
The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
Static friction
Dynamic friction
Limiting friction
Coefficient of friction
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
The bellow figure shows the three coplanar forces P, Q and R acting at a point O. If these forces are in equilibrium, then 
P/sin β = Q/sin α = R/sin
P/sin α = Q/sin β = R/sin
P/sin = Q/sin α = R/sin β
P/sin α = Q/sin = R/sin β
Non-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
The resolved part of the resultant of two forces inclined at an angle θ in a given direction is equal to
The algebraic sum of the resolved parts of the forces in the given direction
The sum of the resolved parts of the forces in the given direction
The difference of the forces multiplied by the cosine of θ
The sum of the forces multiplied by the sine of θ
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
When the lift is moving upwards with some acceleration, the pressure exerted by a man is __________ to its acceleration.
Directly proportional
Inversely proportional
Cube root
None of these
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