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## Machine Design MCQ Set 1

1. Which of the following statements are associated with complete dynamic balancing of rotating systems?
1. Resultant couple due to all inertia forces is zero.
2. Support reactions due to forces are zero but not due to couples.
3. The system is automatically statically balanced.
4. Centre of masses of the system lies on the axis of rotation.
a) 1, 2, 3 and 4
b) 1, 2, and 3 only
c) 2, 3 and 4 only
d) 1, 3 and 4 only

Answer: d [Reason:] Support reactions due to forces & couple both need to be zero.

2. Which of the following statements is correct about the balancing of a mechanical system?
a) If it is under static balance, then there will be dynamic balance also
b) If it is under dynamic balance, then there will be static balance also
c) Both static as well as dynamic balance have to be achieved separately
d) None of the mentioned

Answer: c [Reason:] Complete balancing means both static & dynamic should be balanced.

3. The magnitude of swaying couple due to partial balance of the primary unbalancing force in locomotive is
a) inversely proportional to the reciprocating mass
b) directly proportional to the square of the distance between the centre lines of the two cylinders
c) inversely proportional to the distance between the centerlines of the two cylinders
d) directly proportional to the distance between the centerlines of the two cylinders

4. In a locomotive, the ratio of the connecting rod length to the crank radius is kept very large in order to
a) minimize the effect of primary forces
b) minimize the effect of secondary forces
c) have perfect balancing
d) start the locomotive conveniently

Answer: b [Reason:] As l increases FS decreases Hence the ratio is kept large to avoid secondary forces for each balancing.

5. In balancing of single-cylinder engine, the rotating unbalance is
a) completely made zero and so also the reciprocating unbalance
b) completely made zero and the reciprocating unbalance is partially reduced
c) partially reduced and the reciprocating unbalance is completely made zero
d) partially reduced and so also the reciprocating unbalance

Answer: b [Reason:] In balancing of single-cylinder engine, the rotating unbalance is completely made zero and the reciprocating unbalance is partially reduced.

6. In case of partial balancing of locomotives, the maximum magnitude of the unbalanced force perpendicular to the line of stroke is called hammer blow and this has to be limited by proper choice of the balancing mass and its radial position.
a) True
b) False

Answer: a [Reason:] The effect of hammer blow is to cause variation in pressure between the wheel and the rail, and it may sometimes cause the lifting of wheels from the rails.

7. Multi-cylinder engines are desirable because
a) only balancing problems are reduced
b) only flywheel size is reduced
c) both (a) and (b)
d) none of the mentioned

8. When the primary direct crank of a reciprocating engine makes an angle θ with the line of stroke, then the secondary direct crank will make an angle of . . . . . with the line of stroke.
a) θ /2
b) θ
c) 2 θ
d) 4 θ

Answer: c [Reason:] The secondary direct crank angle is always twice of primary direct crank angle.

9. Secondary forces in reciprocating mass on engine frame are
a) of same frequency as of primary forces
b) twice the frequency as of primary forces
c) four times the frequency as of primary forces
d) none of the mentioned

10. The secondary unbalanced force produced by the reciprocating parts of a certain cylinder of a given engine with crank radius r and connecting rod length l can be considered as equal to primary unbalanced force produced by the same weight having
a) an equivalent crank radius r2/4l and rotating at twice the speed of the engine
b) r2/4l as equivalent crank radius and rotating at engine speed
c) equivalent crank length of r2/4l and rotating at engine speed
d) none of the mentioned

Answer: a [Reason:] We know that secondary force = primary force FS = FP Therefore, to balance the force the primary force should contain an equivalent crank radius r2/4l and rotating at twice the speed of the engine.

11. Which of the following statement is correct?
a) In any engine, 100% of the reciprocating masses can be balanced dynamically
b) In the case of balancing of multicylinder engine, the value of secondary force is higher than the value of the primary force
c) In the case of balancing of multimass rotating systems, dynamic balancing can be directly started without static balancing done to the system
d) none of the mentioned

## Machine Design MCQ Set 2

1. The brakes commonly used in railway trains is
a) shoe brake
b) band brake
c) band and block brake
d) internal expanding brake

Answer: a [Reason:] A single block or shoe brake consists of a block or shoe which is pressed against the rim of a revolving brake wheel drum. The block is made of a softer material than the rim of the wheel. This type of a brake is commonly used on railway trains and tram cars.

2. The brake commonly used in motor cars is
a) shoe brake
b) band brake
c) band and block brake
d) internal expanding brake

Answer: d [Reason:] The internal expanding type of brake is commonly used in motor cars and light trucks.

3. When brakes are applied to all the four wheels of a moving car, the distance travelled by the car before it is brought to rest, will be
a) maximum
b) minimum
c) equal
d) none of the mentioned

Answer: b [Reason:] When the brakes are applied to all the four wheels, the braking distance (i.e. the distance in which the vehicle is brought to rest after applying the brakes) will be the least. It is due to this reason that the brakes are applied to all the four wheels.

4. Which of the following is an absorption type dynamometer ?
a) prony brake dynamometer
b) epicyclic-train dynamometer
c) torsion dynamometer
d) none of the mentioned

Answer: a [Reason:] Absorption type dynamometers are 1. Prony brake dynamometer, 2. Rope brake dynamometer.

5. The transmission type of dynamometer is a
a) prony brake dynamometer
b) epicyclic-train dynamometer
c) torsion dynamometer
d) none of the mentioned

Answer: c [Reason:] Transmission type dynamometers are 1. Epicyclic-train dynamometer, 2. Belt transmission dynamometer, 3. Torsion dynamometer.

6. The material used for the brake lining should have
a) It should have low wear rate.
b) It should have high heat resistance.
c) It should have high heat dissipation capacity.
d) All of the mentioned

Answer: d [Reason:] The material used for the brake lining should have the following characteristics: 1. It should have high coefficient of friction with minimum fading. 2. It should have low wear rate. 3. It should have high heat resistance. 4. It should have high heat dissipation capacity. 5. It should have adequate mechanical strength. 6. It should not be affected by moisture and oil.

7. The capacity of a brake depends upon
a) The unit pressure between the braking surfaces,
b) The coefficient of friction between the braking surfaces,
c) The peripheral velocity of the brake drum
d) All of the mentioned

Answer: d [Reason:] The capacity of a brake depends upon the following factors : 1. The unit pressure between the braking surfaces, 2. The coefficient of friction between the braking surfaces, 3. The peripheral velocity of the brake drum, 4. The projected area of the friction surfaces, and 5. The ability of the brake to dissipate heat equivalent to the energy being absorbed.

8. For high speed engines, the cam follower should move with
a) uniform velocity
b) simple harmonic motion
c) uniform acceleration and retardation
d) cyclodial motion

Answer: d [Reason:] For high speed engines, the cam follower should move with cyclodial motion. For S.H.M. cam, the acceleration of the follower at the ends of the stroke and aimed stroke respectively, is maximum and zero.

## Machine Design MCQ Set 3

1. The size of a cam depends upon
a) base circle
b) pitch circle
c) prime circle
d) pitch curve

Answer: a [Reason:] Base circle is the smallest circle that can be drawn to the cam profile. Pitch circle is a circle drawn from the centre of the cam through the pitch points. Prime circle is the smallest circle that can be drawn from the centre of the cam and tangent to the pitch curve.

2. The angle between the direction of the follower motion and a normal to the pitch curve is called
a) pitch angle
b) prime angle
c) base angle
d) pressure angle

Answer: d [Reason:] It is the angle between the direction of the follower motion and a normal to the pitch curve. This angle is very important in designing a cam profile. If the pressure angle is too large, a reciprocating follower will jam in its bearings.

3. A circle drawn with centre as the cam centre and radius equal to the distance between the cam centre and the point on the pitch curve at which the pressure angle is maximum, is called
a) base circle
b) pitch circle
c) prime circle
d) none of the mentioned

Answer: b [Reason:] Base circle is the smallest circle that can be drawn to the cam profile. Pitch circle is a circle drawn from the centre of the cam through the pitch points. Prime circle is the smallest circle that can be drawn from the centre of the cam and tangent to the pitch curve.

4. The cam follower generally used in automobile engines is
a) knife edge follower
b) flat faced follower
c) spherical faced follower
d) roller follower

Answer: c [Reason:] When the contacting end of the follower is of spherical shape, it is called a spherical faced follower. It may be noted that when a flat-faced follower is used in automobile engines, high surface stresses are produced. In order to minimise these stresses, the flat end of the follower is machined to a spherical shape.

5. The cam follower extensively used in air-craft engines is
a) knife edge follower
b) flat faced follower
c) spherical faced follower
d) roller follower

Answer: d [Reason:] When the contacting end of the follower is a roller, it is called a roller follower. Since the rolling motion takes place between the contacting surfaces (i.e. the roller and the cam), therefore the rate of wear is greatly reduced. In roller followers also the side thrust exists between the follower and the guide. The roller followers are extensively used where more space is available such as in stationary gas and oil engines and aircraft engines.

6. In a radial cam, the follower moves
a) in a direction perpendicular to the cam axis
b) in a direction parallel to the cam axis
c) in any direction irrespective of the cam axis
d) along the cam axis

Answer: a [Reason:] In radial cams, the follower reciprocates or oscillates in a direction perpendicular to the cam axis.

7. A radial follower is one
a) that reciprocates in the guides
b) that oscillates
c) in which the follower translates along an axis passing through the cam centre of rotation.
d) none of the mentioned

Answer: a [Reason:] When the motion of the follower is along an axis passing through the centre of the cam, it is known as radial follower.

8. Ofset is provided to a cam follower mechanism to
a) minimise the side thrust
b) accelerate
c) avoid jerk
d) none of the mentioned

Answer: a [Reason:] When the motion of the follower is along an axis away from the axis of the cam centre, it is called off-set follower.

9. For low and moderate speed engines, the cam follower should move with
a) uniform velocity
b) simple harmonic motion
c) uniform acceleration and retardation
d) cycloidal motion

10. For high speed engines, the cam follower should move with
a) uniform velocity
b) simple harmonic motion
c) uniform acceleration and retardation
d) cycloidal motion

Answer: d [Reason:] Since with high speed engines, maximum acceleration is required and that is possible only through cycloidal motion.

11. Which of the following displacement diagrams should be chosen for better dynamic performance of a cam-follower mechanism ?
a) simple hormonic motion
b) parabolic motion
c) cycloidal motion
d) none of the mentioned

Answer: c [Reason:] Only cycloidal motion gives maximum acceletation. Hence, it is considered the most dynamic cam- follower mechanism.

12. The linear velocity of the reciprocating roller follower when it has contact with the straight flanks of the tangent cam, is given by
a) ω(r1-r2)sinθ
b) ω(r1-r2)cosθ
c) ωr1+r2)sinθsec2θ
d) ω(r1+r2)cosθcosec2θ

Answer: c [Reason:] Velocity = ωr1+r2)sinθsec2θ where ω = Angular velocity of the cam shaft, r1 = Minimum radius of the cam, r2 = Radius of the roller, and θ = Angle turned by the cam from the beginning of the displacement for contact of roller with the straight flanks.

13. The displacement of a flat faced follower when it has contact with the flank of a circular arc cam, is given by
a) R(1-cosθ)
b) R(1-sinθ)
c) (R-r1)(1-cosθ)
d) (R-r1)(1-sinθ)

Answer: c [Reason:] Displacement = (R-r1)(1-cosθ) where R = Radius of the flank, r1 = Minimum radius of the cam, and θ = Angle turned by the cam for contact with the circular flank.

14. The retardation of a flat faced follower when it has contact at the apex of the nose of a circular arc cam, is given by
a) ω2×OQ
b) ω2×OQsinθ
c) ω2×OQcosθ
d) ω2×OQtanθ

Answer: a [Reason:] Retardation is maximum when α−θ = 0 or θ = α , Maximum retardation = ω2×OQ where OQ = Distance between the centre of circular flank and centre of nose.

## Machine Design MCQ Set 4

1. Cam size depends upon
a) base circle
b) pitch circle
c) prime circle
d) outer circle

Answer: a [Reason:] Cam size depends upon base circle. The pressure angle of a cam depends upon offset between centre lines of cam and follower,lift of follower and angle of ascent.

2. Angle of ascent of cam is defined as the angle
a) during which the follower returns to its initial position
b) of rotation of the cam for a definite displacement of the follower
c) through which the cam rotates during the period in which the follower remains in highest position
d) moved by the cam from the instant the follower begins to rise, till it reaches its highest position

Answer: d [Reason:] Angle of ascent of cam is defined as the angle moved by the cam from the instant the follower begins to rise, till it reaches its highest position. Angle of action of cam is defined as the angle moved by the cam from beginning of ascent to the termination of descent.

3. The pressure angle of a cam depends upon
a) offset between centre lines of cam and follower
b) lift of follower
c) angle of ascent
d) all of the mentioned

Answer: d [Reason:] Cam size depends upon base circle. The pressure angle of a cam depends upon offset between centre lines of cam and follower,lift of follower and angle of ascent.

4. Angle of action of cam is defined as the angle
a) of rotation of the cam for a definite displacement of the follower
b) through which the cam rotates during the period in which the follower remains in the highest position
c) moved by the cam from the instant the follower begins to rise, till it reaches its highest position
d) moved by the cam from beginning of ascent to the termination of descent

Answer: d [Reason:] Angle of ascent of cam is defined as the angle moved by the cam from the instant the follower begins to rise, till it reaches its highest position. Angle of action of cam is defined as the angle moved by the cam from beginning of ascent to the termination of descent.

5. Throw of a cam is the maximum distance of the follower from
a) base circle
b) pitch circle
c) root circle
d) prime circle

Answer: a [Reason:] Cam size depends upon base circle. Throw of a cam is the maximum distance of the follower from base circle.

6. Cylindrical cams can be classified as
a) circular
b) tangent
c) reciprocating
d) none of the mentioned

Answer: d [Reason:] A cylindrical cam or barrel cam is a cam in which the follower rides on the surface of a cylinder. In the most common type, the follower rides in a groove cut into the surface of a cylinder. These cams are principally used to convert rotational motion to linear motion parallel to the rotational axis of the cylinder. A cylinder may have several grooves cut into the surface and drive several followers.

7. The cam follower generally used in aircraft engines is
a) knife edge follower
b) flat faced follower
c) spherical faced follower
d) roller follower

Answer: d [Reason:] The roller followers are extensively used where more space is available such as in stationary gas and oil engines and aircraft engines.

8. For S.H.M. cam, the acceleration of the follower at the ends of the stroke and aimed stroke respectively, is
a) maximum and zero
b) zero and maximum
c) minimum and maximum
d) zero and minimum

Answer: a [Reason:] For high speed engines, the cam follower should move with cyclodial motion. For S.H.M. cam, the acceleration of the follower at the ends of the stroke and aimed stroke respectively, is maximum and zero.

9. Cam angle is defined as the angle
a) during which the follower returns to its initial position
b) of rotation of the cam for a definite displacement of the follower
c) through which, the cam rotates during the period in which the follower remains in the highest position
d) moved by the cam from the instant the follower begins to rise, till it reaches its highest position

Answer: b [Reason:] Cam angle is defined as the angle of rotation of the cam for a definite displacement of the follower. Angle of ascent of cam is defined as the angle moved by the cam from the instant the follower begins to rise, till it reaches its highest position. Angle of action of cam is defined as the angle moved by the cam from beginning of ascent to the termination of descent.

## Machine Design MCQ Set 5

1. In the following geometric modelling techniques, which cannot be used for finite element analysis:
a) Wireframe modelling
b) Surface modelling
c) Solid modelling
d) None of the mentioned

2. In the following geometric primitives, which is not a solid entity of CSG modelling:
a) Box
b) Cone
c) Cylinder
d) Circle

Answer: d [Reason:] In 3D computer graphics and CAD CSG is often used in procedural modeling. CSG can also be performed on polygonal meshes, and may or may not be procedural and/or parametric.Typically they are the objects of simple shape: cuboids, cylinders, prisms, pyramids, spheres, cones.

3. The number of lines required to represent a cube, in a wireframe model is:
a) 8
b) 6
c) l2
d) I6

4. Which of the following is not an analytical entity?
a) Line
b) Circle
c) Spline
d) Parabola

Answer: c [Reason:] In mathematics, a spline is a numeric function that is piecewise-defined by polynomial functions, and which possesses a high degree of smoothness at the places where the polynomial pieces connect.

5. Which of the following is not a synthetic entity?
a) Hyperbola
b) Bezier curve
c) B-spline curve
d) Cubic spline curve

Answer: a [Reason:] he hyperbola is one of the three kinds of conic section, formed by the intersection of a plane and a double cone.

6. Which one of the following does not belong to the family of conics?
a) Parabola
b) Ellipse
c) Hyperbola
d) Line

Answer: d [Reason:] A line is a straight one-dimensional figure having no thickness and extending infinitely in both directions. A line is sometimes called a straight line or, more archaically, a right line.

7. The number of tangents required to describe cubic splines is:
a) 2
b) 1
c) 3
d) 4

Answer: b [Reason:] Since the order of cubic spline is one, therefore only only tangent is required to describe it.

8. The order of the cubic spline is the
a) 2″ order
b) 3″ order
c) 1″ order
d) 4″ order

Answer: c [Reason:] As only one tangent is required to describe cubic spline, therefore its order is 1.

9. The shape of the Bezier curve is controlled by:
a) Control points
b) Knots
c) End points
d) All of the mentioned