laboursonline – MCQs, Mock Tests | Engineering Civil Engineering [MCQS] Applied Mechanics Section -1

The centre of gravity of a triangle is at the point where three

1. medians of the triangle meet
2. perpendicular bisectors of the sides of the triangle meet
3. bisectors of the angle of the triangle meet
4. none of these.

✅ Correct Answer: 1

The forces which meet at one point and have their lines of action in different planes are called

1. coplaner non-concurrent forces
2. non-coplaner concurrent forces
3. non-coplaner non-current forces
4. intersecting forces

✅ Correct Answer: 2

At a given instant ship A is travelling at 6 km/h due east and ship B is travelling at 8 km/h due north. The velocity of B relative to A is

1. 7 km/hrs
2. 2 km/hrs
3. 1km/hrs
4. 10 km/hrs

✅ Correct Answer: 4

The equation of motion of a particle starting from rest along a straight line is x = t3 - 3t2 + 5. The ratio of the accelerations after 5 sec and 3 sec will be

1. 2
2. 3
3. 4
4. 5

✅ Correct Answer: 1

The locus of the instantaneous centre of a moving rigid body, is

1. straight line
2. involute
3. centroid
4. spiral.

✅ Correct Answer: 3

A projectile is thrown at an angle a to the horizontal with α velocity v. It will have the maximum centripetal acceleration

1. at the start
2. at the top of the trajectory
3. as it strikes the ground
4. else where.

✅ Correct Answer: 1

If a body moves in such a way that its velocity increases by equal amount in equal intervals of time, it is said to be moving with

1. a uniform retardation
2. a uniform acceleration
3. a variable acceleration
4. a variable retardation

✅ Correct Answer: 3

If the gravitational accelerational at any place is doubled, the weight of a body, will

1. be reduced to half
2. be doubled
3. not be affected
4. none of these.

✅ Correct Answer: 2

A cable loaded with 0.5 tonne per horizontal metre span is stretched between supports in the same horizontal line 400 m apart. If central dip is 20 m, the minimum tension in the cable, will be

1. 200 tonnes at the centre
2. 500 tonnes at the centre
3. 200 tonnes at the right support
4. 200 tonnes at the left support.

✅ Correct Answer: 2

The Law of Polygon of Forces states that

1. if a polygen representing the forces acting at point in a body is closed, the forces are in equilibrium
2. if forces acting on a point can be represented in magnitde and direction by the sides of a polygon taken in order, then the resultant of the forces will be represented in magnitude and direction by th
3. if forces acting on a point can be represented of a polygon taken in order, their sides of a polygon taken in order, their resultant will be represented in magnitude and direction by the closing side
4. if forces acting on a point can be represented in magnitude and direction by the sides of a polygon in order, the forces are in equilibrium.

✅ Correct Answer: 3

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

1. its longer side"
2. its shorter side"
3. the diagonal of the parallelogram which does not pass through the point of intersection of the forces"
4. the diagonal of the parallelogram which passes through the point of intersection of the forces"

✅ Correct Answer: 4

Which one of the following statements is true ?

1. The tangent of the angle of friction is equal to coefficeint of friction
2. The angle of repose is equal to angle of friction
3. The tangent of the angle of repose is equal to coefficient of friction
4. All the above.

✅ Correct Answer: 4

The product of mass and velocity of a moving a body, is called

1. moment
2. momentum
3. power
4. impulse.

✅ Correct Answer: 2

Engineer's units of force, is

1. Newton in absolute units
2. Dyne in absolute units
3. Newton and dyne in absolute units
4. All the above.

✅ Correct Answer: 1

Joule is the unit of

1. work
2. force
3. power
4. torque

✅ Correct Answer: 1

The maximum velocity of a body vibrating with a simple harmonic motion of amplitude 150 mm and frequency 2 vibrations/sec, is

1. 188.5 m/sec
2. 18.85 m/sec
3. 1.885 m/sec
4. 0.18845 m/sec.

✅ Correct Answer: 3

The masses of two balls are in the ratio of 2 : 1 and their respective velocities are in the ratio of 1 : 2 but in opposite direction before impact. If the coefficient of restitution is , the velocities of separation of the balls will be equal to

1. original velocity in the same direction
2. half the original velocity in the same direction
3. half the original velocity in the opposite direction
4. original velocity in the opposite direction

✅ Correct Answer: 4

The angle which an inclined surface makes with the horiontal when a body placed on it is on the point of moving down, is called

1. angle of repose
2. angle of friction
3. angle of inclination
4. none of these.

✅ Correct Answer: 1

Work may be defined as

1. force x distance
2. force x velocity
3. force x acceleration
4. none of these.

✅ Correct Answer: 1

A bullet weighing 200 g is fired horizontally with a velocity of 25 m/sec from a gun carried on a carriage which together with the gun weighs 100 kg. The velocity of recoil of the gun, will be

1. 0.01 m/sec
2. 0.05 m/sec
3. 1.00 m/sec
4. 1.5 m/see.

✅ Correct Answer: 2

The tension in a cable supporting a lift

1. is more when the lift is moving downwards
2. is less when the lift is moving upwards
3. remains constant whether its moves downwards or upwards
4. is less when the lift is moving downwards.

✅ Correct Answer: 4

A satellite moves in its orbit around the earth due to

1. Gravitational force
2. Centripetal force
3. Centrifugal force
4. none of these.

✅ Correct Answer: 2

If three rigid rods are hinged together to form a triangle and are given rotary as well as translatory motion, the number of instantaneous centres of the triangle, will be

1. 1
2. 2
3. 3
4. 4

✅ Correct Answer: 3

The mechanical advantage of an ideal machine is 100. For moving the local through 2 m, the effort moves through

1. 0.02 m
2. 2 m
3. 2.5 m
4. 20 m.

✅ Correct Answer: 1

When a body in equilibrium undergoes an infinitely small displacement, work imagined to be done, is known as

1. imaginary work
2. negative work
3. virtual work
4. none of these.

✅ Correct Answer: 3

To attain the synchronous orbit, the launch of a satellite, is done from a place

1. on equator
2. on 30° latitude
3. on 45° latitude
4. on 60° latitude

✅ Correct Answer: 1

Pick up the correct statement from the following :

1. Nature plays an important role in the launch of a satellite
2. The earth's gravity reduces the speed of a satellite by 32 km per second
3. The gravitational force relents as the satellite climbs higher
4. All the above.

✅ Correct Answer: 4

If the radius of the earth is 600 km the height of a mountain above sea level at the top of which a beat seconds pendulum at sea level, looses 27 seconds a day, is

1. 500 metres
2. 1000 metres
3. 1500 metres
4. 2000 metres

✅ Correct Answer: 4

The total time of collision and restitution of two bodies, is called

1. time of collision
2. period of collision
3. period of impact
4. all the above.

✅ Correct Answer: 4

The length of a Second's pendulum, is

1. 99.0 mm
2. 99.4 mm
3. 100 cm
4. 101 cm

✅ Correct Answer: 2

A load of 500 kg was lifted through a distance of 13 cm. by an effort of 25 kg which moved through a distance of 650 cm. The efficiency of the lifting machine is

1. 50%
2. 40%
3. 55%
4. 30%

✅ Correct Answer: 2

A string of length 90 cm is fastened to two points A and B at the same level 60 cm apart. A ring weighing 120 g is slided on the string. A horizontal force P is applied to the ring such that it is in equilibrium vertically below B. The value of P is :

1. 40 g
2. 60 g
3. 80 g
4. 100 g

✅ Correct Answer: 3

Two forces act an angle of 120°. If the greater force is 50 kg and their resultant is perpendicular to the smaller force, the smaller force is

1. 20 kg
2. 25 kg
3. 30 kg
4. 35 kg

✅ Correct Answer: 2

The C.G. of a right circular cone lies on its axis of symmetry at a height of

1. h/2
2. h/3
3. h/4
4. h/5

✅ Correct Answer: 3

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

1. 40 kg
2. 60 kg
3. 10 kg
4. 100 kg

✅ Correct Answer: 3

If a particle is projected inside a horizontal tunnel which is 554 cm high with a velocity of 60 m per sec, the angle of projection for maximum range, is

1. 8°
2. 9°
3. 10°
4. 11°

✅ Correct Answer: 3