Lami's theorem states that
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
Correct Answer :
D. If three forces acting at a point are in equilibrium, each force is proportional to the sine of the angle between the other two
Related Questions
A number of forces acting at a point will be in equilibrium, if
All the forces are equally inclined
Sum of all the forces is zero
Sum of resolved parts in the vertical direction is zero (i.e. ΣV = 0)
None of these
The periodic time of one oscillation for a simple pendulum is (where l = Length of the pendulum.)
(1/2π). √(l/g)
(1/2π). √(g/l)
2π. √(l/g)
None of these
The velocity ratio for the first system of pulleys is (where n is the number of pulleys.)
n
n²
2n
2n - 1
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
Which of the following are vector quantities?
Angular displacement
Angular velocity
Angular acceleration
All of these
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
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
Moment of inertia of a rectangular section having width (b) and depth (d) about an axis passing through its C.G. and parallel to the depth (d), is
db3/12
bd³/12
db³/36
bd³/36
When the spring of a watch is wound, it will possess
Strain energy
Kinetic energy
Heat energy
Electrical energy
In a screw jack, the effort required to lower the load is __________ the effort required to raise the same load.
Less than
Equal to
More than
None of these
One watt is equal to
0.1 joule/s
1 joule/s
10 joules/s
100 joules/s
The velocity of a particle moving with simple harmonic motion is __________ at the mean position.
Zero
Minimum
Maximum
None of these
Which of the following is not the unit of energy?
kg m
kcal
Watt
Watt hours
The power developed by a body acted upon by a torque T Newton metre (N - m) and revolving at ω radian/s is given by
T.ω (in watts)
T.ω/60 (in watts)
T.ω/75 (in kilowatts)
T.ω/4500 (in kilowatts)
The static friction
Bears a constant ratio to the normal reaction between the two surfaces
Is independent of the area of contact, between the two surfaces
Always acts in a direction, opposite to that in which the body tends to move
All of the above
Forces are called coplanar when all of them acting on body lie in
One point
One plane
Different planes
Perpendicular planes
The maximum efficiency of a lifting machine is
1/m
V.R./m
m/V.R.
1/(m × V.R.)
Dynamic friction as compared to static friction is
Same
More
Less
May be less of more depending on nature of surfaces and velocity
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
If a given force (or a given system of forces) acting on a body __________ the position of the body, but keeps it in equilibrium, then its effect is to produce internal stress in the body.
Change
Does not change
Changes periodically
None of these
A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. Select the correct reason from the following:
Both the balls undergo an equal change in momentum
The change in momentum suffered by rubber ball is more than the lead ball
The change in momentum suffered by rubber ball is less than the lead ball
None of the above
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
In the shown figure, if the angle of inclination of the plane is increased, then acceleration of the system will 
Increase
Decrease
Remain the same
None of these
Which of the following statement is correct?
The kinetic energy of a body during impact remains constant.
The kinetic energy of a body before impact is equal to the kinetic energy of a body after impact.
The kinetic energy of a body before impact is less than the kinetic energy of a body after impact.
The kinetic energy of a body before impact is more than the kinetic energy of a body after impact.
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 differential pulley block has larger and smaller diameters of 100 mm and 80 mm respectively. Its velocity ratio is
5
10
20
40
The three forces of 100 N, 200 N and 300 N have their lines of action parallel to each other but act in the opposite directions. These forces are known as
Coplanar concurrent forces
Coplanar non-concurrent forces
Like parallel forces
Unlike parallel forces
The mechanical advantage of a lifting machine is the ratio of
Distance moved by effort to the distance moved by load
Load lifted to the effort applied
Output to the input
All of the above
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
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