laboursonline – MCQs, Mock Tests | Engineering Civil Engineering [MCQS] Applied Mechanics Section -5

The centre of gravity of a homogenous body is the point at which the whole

1. volume of the body is assumed to be concentrated
2. area of the surface of the body is assumed to be concentrated
3. weight of the body is assumed to be concentrated
4. all the above.

✅ Correct Answer: 3

Pick up the correct statement from the following :

1. If two equal and perfectly elastic smooth spheres impinge directly, they interchange their velocities.
2. If a sphere impinges directly on an equal sphere which is at rest, then a fraction (1 - e2) the original kinetic energy is lost by the impact.
3. If a smooth sphere impinges on another sphere, which is at rest, the latter will move along the line of centres.
4. All the above.

✅ Correct Answer: 4

Centre of gravity of a thin hollow cone lies on the axis of symmmetry at a height of

1. one-half of the total height above base
2. one-third of the total height above base
3. one-fourth of the total height above base
4. none of these.

✅ Correct Answer: 2

A ball of mass 1 kg moving with a velocity of 2 m/sec collides a stationary ball of mass 2 kg and comes to rest after impact. The velocity of the second ball after impact will be

1. zero
2. 0.5 m/sec
3. 1.0 m/sec
4. 2.0 m/sec.

✅ Correct Answer: 3

Periodic time of a particle moving with simple harmonic motion is the time taken by the particle for

1. half oscillation
2. quarter oscillation
3. complete oscillation
4. none of these.

✅ Correct Answer: 3

The motion of a bicycle wheel is

1. translatory
2. rotary
3. rotary and translatory
4. curvilinear

✅ Correct Answer: 3

A particle moving with a simple harmonic motion, attains its maximum velocity when it passes

1. the extreme point of the oscillation
2. through the mean position
3. through a point at half amplitude
4. none of these.

✅ Correct Answer: 2

The practical units of work, is

1. erg
2. joule
3. Newton
4. dyne.

✅ Correct Answer: 4

The rate of change of displacement of a body with respect to its surrounding, is known

1. velocity
2. acceleration
3. speed
4. none of these.

✅ Correct Answer: 3

The Centre of gravity of a 10 x 15 x 5 cm T section from its bottom, is

1. 7.5 cm
2. 5.0 cm
3. 8.75 cm
4. 7.85 cm

✅ Correct Answer: 3

For a self-locking machine, the efficiency should be

1. less than 60%
2. 50%
3. more than 50%
4. None of these.

✅ Correct Answer: 1

When a body moves round a fixed axis, it has

1. a rotary motion
2. a circular motion
3. a translatory
4. a rotary motion and translatory motion.

✅ Correct Answer: 2

From a solid cylinder of height 8 cm and radius 4 cm, a right circular cone is scooped out on the same base and having the same height as that of the cylinder. The c.g. of the remainder is at a height of

1. 4.5 cm
2. 5.0 cm
3. 5.25 cm
4. 5.5 cm.

✅ Correct Answer: 2

The rotational velocity of a satellite is increased by 450 m per second if its launch is done from equator

1. eastward
2. northward
3. westward
4. southward

✅ Correct Answer: 1

When a body falls freely under gravitational force, it possesses

1. maximum weight
2. minimum weight
3. no weight
4. no effect on its weight.

✅ Correct Answer: 3

A rigid body suspended Vertically at a point and oscillating with a small amplitude under the action of the force of gravity, is called

1. simple pendulum
2. compour pendulum
3. Second's pendulum
4. none of these.

✅ Correct Answer: 2

If a ball which is dropped from a height of 2.25 m on a smooth floor attains the height of bounce equal to 1.00 m, the coefficient of the restitution between the ball and floor, is

1. 0.25
2. 0.5
3. 0.67
4. 0.33

✅ Correct Answer: 2

The piston of a steam engine moves with a simple harmonic motion. The crank rotates 120 r.p.m. and the stroke length is 2 metres. The linear velocity of the piston when it is at a distance of 0.5 metre from the centre, is

1. 5.88 m/sec
2. 8.88 m/sec
3. 10.88 m/sec
4. 12.88 m/sec.

✅ Correct Answer: 3

The frequency of oscillation on moon as compared to that on earth, will be

1. 2.44 times more
2. 2.44 times less
3. 3 times less
4. 3 times more.

✅ Correct Answer: 2

The velocity ratio of an inclined plane of inclination θ with horizontal for lifting a load is

1. sin θ
2. cos θ
3. tan θ
4. cosec θ.

✅ Correct Answer: 4

Pick up the incorrect statement from the following. In a simple harmonic motion

1. velocity is maximum at its mean position
2. velocity is minimum at the end of the storke
3. acceleration is minimum at the end of the stroke
4. acceleration is zero at the mean position.

✅ Correct Answer: 3

The gravitational force makes a satellite go round the earth in a circular orbit, if it is projected with an initial velocity of

1. 8.04 km/sec at a height of 285 km
2. 11.11 km/sec at a height of 37, 400 km
3. 11.26 km/sec, the satellite escapes the pull of the earth
4. All the above.

✅ Correct Answer: 4

The point about which combined motion of rotation and translation of a rigid body takes place, is known as

1. Virtual centre
2. Instantaneous centre
3. Instantaneous axis
4. All the above.

✅ Correct Answer: 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

1. 16 m/sec
2. 18 m/sec
3. 20 m/sec
4. 22 m/sec

✅ Correct Answer: 3

A point subjected to a number of forces will be in equilibrium, if

1. sum of resolved parts in any two directions at right angles, are both zero
2. algebraic sum of the forces is zero
3. two resolved parts in any two directions at right angles are equal
4. algebraic sum of the moments of the forces about the point is zero

✅ Correct Answer: 1

Periodic time of body moving with simple harmonic motion, is

1. directly proportional to its angular velocity
2. directly porportional to the square of its angular velocity
3. inversly proportional to the square of its angular velocity
4. inversely proportional to its angular velocity.

✅ Correct Answer: 4

On a ladder resting on a rough ground and leaning against a smooth vertical wall, the force of friction acts

1. downwards at its upper end
2. upwards at its upper end
3. perpendicular to the wall at its upper end
4. zero at its upper end

✅ Correct Answer: 4

The centre of gravity of a plane lamina will not be at its geometrical centre if it is a

1. circle
2. equilateral triangle
3. rectangle
4. square

✅ Correct Answer: 4

The motion of a particle moving with S.H.M. from an extremity to the other, constitutes

1. half an oscillation
2. one full oscillation
3. two oscillations
4. none of these.

✅ Correct Answer: 1

Two parallel forces 20 kg and 15 kg act. In order that the distance of the resultant from 20 kg force may be the same as that of the former resultant was from 15 kg, the 20 kg force is diminished by

1. 5.5 kg
2. 6.25 kg
3. 8.75 kg
4. 10.5 kg.

✅ Correct Answer: 3

The velocity of a moving body, is

1. a vector quantity
2. a scalar quantity
3. a constant quantity
4. none of these.

✅ Correct Answer: 1

The centre of gravity of a quadrant of a circle lies along its central radius at a distance of

1. 0.2 R
2. 0.3 R
3. 0.4 R
4. 0.5 R

✅ Correct Answer: 4

A geo-stationary satellite is one which orbits the earth with a velocity of rotation of

1. moon
2. earth
3. sun
4. pole

✅ Correct Answer: 2

The direction of projection should bisect the angle between the inclined plane and the vertical for a range of a projectile on inclined plane

1. to be zero
2. to be maximum
3. to be minimum
4. none of the these.

✅ Correct Answer: 2

If a body is acted upon by a number of coplaner non-concurrent forces, it may

1. rotate about itself without moving
2. move in any one direction rotating about itself
3. be completely at rest
4. all the above.

✅ Correct Answer: 4