laboursonline – MCQs, Mock Tests | Engineering Civil Engineering [MCQS] Applied Mechanics Section -3

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 velocity ratio of the lifting machine is"

1. 50
2. 55
3. 60
4. 65

✅ Correct Answer: 1

The angle of friction is :

1. The ratio of the friction and the normal reaction
2. The force of friction when the body is in motion
3. The angle between the normal reaction and the resultant of normal raction and limiting friction
4. The force of friction at which the body is just about to move.

✅ Correct Answer: 3

The motion of a particle is described by the relation x = t2- 10t + 30, where x is in metres and t in seconds. The total distance travelled by the particle from t = 0 to t = 10 seconds would be

1. zero
2. 30 m
3. 50 m
4. none of these.

✅ Correct Answer: 1

Three forces which act on a rigid body to keep it in equilibrium. The forces must be coplanar and

1. concurrent
2. parallel
3. concurrent parallel
4. none of these.

✅ Correct Answer: 1

For perfectly elastic bodies, the value of coefficient of restitution is

1. zero
2. 0.5
3. 1
4. between 0 and 1.

✅ Correct Answer: 3

The maximum frictional force which comes into play, when a body just begins to slide over the surface of a an other body, is known

1. sliding friction
2. rolling friction
3. limiting friction
4. none of these.

✅ Correct Answer: 3

If two forces of 3 kg and 4 kg act at right angles to each other, their resultant force will be equal to

1. 7 kg
2. 1 kg
3. 5 kg
4. none of these.

✅ Correct Answer: 3

Two shots fired simultaneously from the top and bottom of a vertical tower with elevations of 30° and 45° respectively strike a target simultaneously. If horizontal distance of the target from the tower is 1000 m, the height of the tower is

1. 350 m
2. 375 m
3. 400 m
4. 425 m

✅ Correct Answer: 4

A stone of mass 1 kg is tied to a string of length 1 m and whirled in a horizontal circle at a constant angular speed 5 rad/sec. The tension in the string is

1. 5 N
2. 10 N
3. 15 N
4. 25 N

✅ Correct Answer: 4

The apparent weight of a man in a moving lift is less than his real weight when it is going down with

1. uniform speed
2. an acceleration
3. linear momentum
4. retardation.

✅ Correct Answer: 2

P is the force acting on a body whose mass is m and acceleration is f. The equation P - mf = 0, is known as

1. equation of dynamics
2. equation of dynamic equilibrium
3. equation of statics
4. none of these.

✅ Correct Answer: 1

Newtons's Law of Motion is :

1. Every body continues in its state of rest or of uniform motion, in a straight line, unless it is acted upon by some external force
2. The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction, in which the force acts
3. To every action, there is always an equal and opposite reaction
4. All the above.

✅ Correct Answer: 4

Two particles have been projected at angles 64° and 45° to the horizontal. If the velocity of projection of first is 10 m/sec, the velocity of projection of the other for equal horizontal ranges is

1. 9.3 m/sec
2. 8.3 m/sec
3. 7.3 m/sec
4. 6.3 m/sec.

✅ Correct Answer: 1

The necessary condition of equilibrium of a body, is :

1. algebraic sum of horizontal components of all the forces must be zero
2. algebraic sum of vertical components of all the forces must be zero
3. algebraic sum of the moments of the forces about a point must be zero
4. all (a), (b) and (c).

✅ Correct Answer: 4

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

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

✅ Correct Answer: 4

Principle of Transmissibility of Forces states that, when a force acts upon a body, its effect is

1. maximum if it acts at the centre of gravity of the body
2. different at different points on its line of
3. same at every point on its line of action
4. minimum if it acts at the C.G. of the body

✅ Correct Answer: 3

A ball is dropped from a height of 2.25 m on a smooth floor and rises to a height of 1.00 m after the bounce. The coefficient of restitution between the ball and the floor is

1. 0.33
2. 0.44
3. 0.57
4. 67

✅ Correct Answer: 4

If the linear velocity of a point on the rim of a wheel of 10 m diameter, is 50 m/sec, its angular velocity will be

1. 20 rad/sec
2. 15rad/sec
3. 10 rad/sec
4. 5 rad/sec

✅ Correct Answer: 4

A marble ball is rolled on a smooth floor of a room to hit a wall. If the time taken by the ball in returning to the point of projection is twice the time taken in reaching the wall, the coefficient of restitution between the ball and the wall, is

1. 0.25
2. 0.5
3. 0.75
4. 1

✅ Correct Answer: 2

The force acting on a point on the surface of a rigid body may be considered to act

1. at the centre of gravity of the body
2. on the periphery of the body
3. on any point on the line of action of the force
4. at any point on the surface normal to the line of action of the force.

✅ Correct Answer: 3

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

1. 7000 km per hour
2. 8000 km per hour
3. 10,000 per hour
4. 11,000 km per hour

✅ Correct Answer: 4

Pick up the incorrect statement from the following

1. The C.G. of a circle is at its centre
2. The C.G. of a triangle is at the intersecton of its medians
3. The C.G. of a rectangle is at the intersection of its diagonals
4. The C.G. of a semicircle is at a distance of r/2 from the centre

✅ Correct Answer: 4

A 49 kg lady stands on a spring scale in an elevator. During the first 5 sec, starting from rest, the scale reads 69 kg. The velocity of the elevator will be

1. 10 m/sec
2. 15 m/sec
3. 20 m/sec
4. 25 m/sec

✅ Correct Answer: 3

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

1. rubber and lead balls undergo equal changes in momentum
2. change in momentum suffered by lead ball is less that of rubber ball
3. momentum of rubber ball is less than that of lead ball
4. none of these.

✅ Correct Answer: 4

The instantaneous centre of a member lies at the point of intersection of two lines drawn at the ends of the member such that the lines are inclined to the direction of motion of the ends at

1. 30°
2. 45°
3. 60°
4. 90°

✅ Correct Answer: 4

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

1. 0.5 m/sec
2. 1.0 m/sec
3. 1.5 m/sec
4. 2.5 m/sec

✅ Correct Answer: 2