If the given forces P₁, P₂, P₃ and P₄ are such that the force polygon does not close, then the system will
Be in equilibrium
Always reduce to a resultant force
Always reduce to a couple
Both (A) and (C)
Correct Answer :
B. Always reduce to a resultant force
Related Questions
Two forces of 6 Newtons and 8 Newtons which are acting at right angles to each other, will have a resultant of
5 Newtons
8 Newtons
10 Newtons
12 Newtons
The equation of motion of a particle starting from rest along a straight line is x = t3 - 3l2 + 5. The ratio of the velocities after 5 sec and 3 sec will be
2
3
4
5
A particle moves with a velocity of 2 m/sec in a straight line with a negative acceleration of 0.1 m/sec2. Time required to traverse a distance of 1.5 m, is
40 sec
30 sec
20 sec
15 sec
An ordinate in a funicular polygon represents
Shear force
Resultant force
Bending moment
Equilibrium
A rigid body suspended vertically at a point and oscillating with a small amplitude under the action of the force of gravity, is called
Simple pendulum
Compound pendulum
Second's pendulum
None of these
A satellite is said to move in a synchronous orbit if it moves at an altitude of 36, 000 km with a maximum velocity of about
7000 km per hour
8000 km per hour
9000 km per hour
11,000 km per hour
A disc of mass 4 kg, radius 0.5 m and moment of inertia 3 kgm² rolls on a horizontal surface so that its center moves with speed 5 m/see. Kinetic energy of the disc is
50 J
150 J
200 J
400 J
Parallelogram Law of Forces states, if two forces acting simultaneously on a particle be represented in magnitude and direction by two adjacent sides of a parallelogram, their resultant may be represented in magnitude and direction by
Its longer side
Its shorter side
The diagonal of the parallelogram which does not pass through the point of intersection of the forces
The diagonal of the parallelogram which passes through the point of intersection of the forces
For a simple pendulum, time period for a beat, is
π √(l/g)
π √(2l/g)
π √(g/2l)
π √(l/2g)
A pilot flies a small plane in a vertical loop of radius r. At the top of its trajectory he experiences weightlessness. If the acceleration due to gravity is g, the speed of the plane at the top of its trajectory would be
Zero
Infinite
gr
2gr
A heavy ladder resting on a floor and against a vertical wall may not be in equilibrium, if
Floor is smooth and the wall is rough
Floor is rough and the wall is smooth
Floor and wall both are smooth surfaces
Floor and wall both are rough surfaces
When a body falls freely under gravitational force, it possesses
Maximum weight
Minimum weight
No weight
No effect on its weight
The shape of a suspended cable for a uniformly distributed load over it is
Circular
Parabolic
Catenary
Cubic parabola
A uniform rod 9 m long weighing 40 kg is pivoted at a point 2 m from one end where a weight of 120 kg is suspended. The required force acting at the end in a direction perpendicular to rod to keep it equilibrium, at an inclination 60° with horizontal, is
40 kg
60 kg
10 kg
100 kg
The reaction at the central support B of the beam ABC hinged at D shown in below figure is 
2 t
5.8 t
0.2 t
3.5 t
Newton's law of Collision of elastic bodies states that when two moving bodies collide each other, their velocity of separation
Is directly proportional to their velocity of approach
Is inversely proportional to their velocity of approach
Bears a constant ratio to their velocity of approach
Is equal to the sum of their velocities of approach
One end of a light string 4 m in length is fixed to a point on a smooth wall and the other end fastened to a point on the surface of a smooth sphere of diameter 2.25 m and of weight 100 kg. The tension in the string is
17.5 kg
19.5 kg
22.5 kg
25 kg
The ratio of the ranges on the inclined plane with motion upward and with motion downward for a given velocity, angle of projection will be
sin (α + β)/sin (α - β)
sin (α - β)/sin (α + β)
cos (α - β)/cos (α + β)
tan (α - β)/tan (α + β)
Force polygon method is applicable for
Any coplanar force system
A system of parallel forces only
Concurrent coplanar force system
Non-concurrent coplanar force system
A hoop of radius 3 m weighs 100 kg. It rolls along a horizontal floor so that at its centre of mass has a speed of 200 mm/sec. The work required to stop the hoop is
2 J
4 J
6 J
8 J
A rod 5 m in length is moving in a vertical plane. When it is inclined at 60° to horizontal, its lower end is moving horizontally at 3 m/sec and upper end is moving in vertical direction. The velocity of its upper end, is
0.5 m/sec
1.0 m/sec
1.5 m/sec
2.5 m/sec
ω rad/sec is the angular velocity of a crank whose radius is r. If it makes θ° with inner dead centre and obliquity of the connecting rod l is , the velocity v of the piston, is given by the equation
ω2 (l cos + r sin tan θ)
ω2 (l sin + r cos φ tan θ)
ω (l sin + r cos tan θ)
ω2 (l sin - r cos θ tan )
If two equal forces of magnitude P act at an angle θ, their resultant, will be
P cos θ/2
2P sin θ/2
P tan θ/2
2P cos θ/2
A particle is dropped from the top of a tower 60 m high and another is projected upwards from the foot of the tower to meet the first particle at a height of 15.9 m. The velocity of projection of the second particle is
16 m/sec
18 m/sec
20 m/sec
22 m/sec
For a body moving with simple harmonic motion, the number of cycles per second, is known as its
Oscillation
Amplitude
Periodic time
Frequency
A trolley wire weighs 1 kg per metre length. The ends of the wire are attached to two poles 20 m apart. If the horizontal tension is 1000 kg, the central dip of the cable is
2 cm
3 cm
4 cm
5 cm
According to Law of Triangle of Forces
Three forces acting at a point, can be rep-resented by the sides of a triangle, each side being in proportion to the force
Three forces acting along the sides of a triangle are always in equilibrium
If three forces acting on a, point can be represented in magnitude and direction, by the sides of a triangle taken in order, these will be in equilibrium
If the forces acting on a particle be represented in magnitude and direction by the two sides of a triangle taken in order, their resultant will be represented in magnitude and direction by the third side of the triangle, taken in opposite order
One half of a vibration of a body, is called
Period time
Oscillation
Beat
Amplitude
A point subjected to a number of forces will be in equilibrium, if
Sum of resolved parts in any two directions at right angles, are both zero
Algebraic sum of the forces is zero
Two resolved parts in any two directions at right angles are equal
Algebraic sum of the moments of the forces about the point is zero
Pick up the correct statement from the following. A rubber ball when strikes a wall rebounds but a lead ball of same mass and velocity when strikes the same wall, falls down
Rubber and lead balls undergo equal changes in momentum
Change in momentum suffered by lead ball is less that of rubber ball
Momentum of rubber ball is less than that of lead ball
None of these