Category: Machine Kinematics Objective Questions

250+ TOP MCQs on Interference and Answers

Machine Kinematics Multiple Choice Questions on “Interference”.

1. Which of the following is a disadvantage of involute gears?
a) Occurrence of interference
b) Non occurrence of interference
c) Pressure angle remains constant
d) Face and flank are generated by single curve
Answer: a
Clarification: The disadvantage of the involute teeth is that the interference occurs. This may be avoided by altering the heights of addendum and dedendum of the mating teeth.

2. By changing the angle of obliquity of the teeth, interference can be avoided.
a) True
b) False
Answer: a
Clarification: Interference can be avoided by changing the obliquity of the teeth or alternatively altering the height of the addendum. Failure to do so will result in the occurrence of interference.

3. The phenomenon when the tip of tooth undercuts the root on its mating gear is known as _______
a) Involution
b) Interference
c) Cycloidal motion
d) Undercutting
Answer: a
Clarification: The phenomenon when the tip of tooth undercuts the root on its mating gear is known as interference. This is generally observed in involute profiles.

4. In which of the following gears, interference occurs?
a) Cycloidal
b) Involute
c) Epi cycloidal
d) Hypo-cycloidal
Answer: b
Clarification: Interference occurs in involute gears which is one of its disadvantages amongst many advantages. This happens when the pinion has a low number of teeth.

5. For the same pitch, which of the following statement is true?
a) Cycloidal gears are stronger than involute gears
b) Involute gears are stronger than cycloidal gears
c) Both cycloidal and Involute gears have equal strength
d) Cycloidal gears are stronger for lower pitch only
Answer: a
Clarification: Cycloidal teeth have wider flanks, as a consequence the cycloidal gears are stronger than the involute gears, provided the pitch is the same. That is why cycloidal gears are used for cast teeth.

6. If the point of contact between the two teeth is always on the involute profiles of both the teeth, then which of the phenomenon will occur?
a) Avoidance of interference
b) Occurrence of interference
c) Increase in length of path of contact
d) Increase in length of arc of contact
Answer: a
Clarification: The interference may only be avoided, if the point of contact between the two teeth is always on the involute profiles of both the teeth.

7. Given,
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the addendum height for the larger gear wheel in mm.
a) 6.5
b) 6
c) 6.8
d) 7
Answer: a
Clarification: r = m.t/2 = 100mm
R = 200mm
Using the constraint we find that
Ra = 206.5mm
Therefore
Addendum height = 6.5mm.

8. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the addendum height for the smaller gear wheel in mm.
a) 6.4
b) 6.2
c) 6.3
d) 6
Answer: b
Clarification: r = m.t/2 = 100mm
R = 200mm
Using the constraint we find that
ra = 106.2mm
Therefore
Addendum height = 6.2mm.

9. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the length of path of contact in mm.
a) 56.4
b) 56.2
c) 56.3
d) 51.3
Answer: d
Clarification: r = m.t/2 = 100mm
R = 200mm
We know that length of path of contact = (R+r)sinΦ/2
= 51.3mm.

10. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the length of arc of contact in mm.
a) 56.4
b) 54.6
c) 56.3
d) 51.3
Answer: b
Clarification: r = m.t/2 = 100mm
R = 200mm
We know that length of path of contact = (R+r)sinΦ/2
= 51.3mm
Arc of contact = length of path of contact / cosΦ
= 54.6mm.

11. Given:
Involute profile teeths of mating gear: 20 and 40
Pressure angle = 20°
module = 10mm
The constraint: The addendum on each wheel is to be made of such a length that the line of contact on each side of the pitch point has half the maximum possible length.
Find the contact ratio.
a) 1.23
b) 1.52
c) 1.74
d) 1.97
Answer: c
Clarification: r = m.t/2 = 100mm
R = 200mm
We know that length of path of contact = (R+r)sinΦ/2
= 51.3mm
Pitch = πx10 = 31.42
Contact ratio = length of path of contact/pitch
= 1.74.

250+ TOP MCQs on Relation Between Linear Motion and Angular Motion and Answers

Machine Kinematics Questions and Answers for Freshers on “Relation Between Linear Motion and Angular Motion”.

1. Which of the following disciplines provides study of inertia forces arising from the combined effect of the mass and motion of the parts?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: d
Clarification: The study of inertia forces arising from the combined effect of the mass and motion of the parts is called kinetics.
The study of relative motion between the parts of a machine is called kinematics.
The study of the relative motion between the parts of a machine and the forces acting on the parts is called theory of machines.

2. Which of the following disciplines provides study of relative motion between the parts of a machine?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: c
Clarification: The study of inertia forces arising from the combined effect of the mass and motion of the parts is called kinetics.
The study of relative motion between the parts of a machine is called kinematics.
The study of the relative motion between the parts of a machine and the forces acting on the parts is called theory of machines.

3. Which of the following disciplines provides study of the relative motion between the parts of a machine and the forces acting on the parts?
a) theory of machines
b) applied mechanics
C) kinematics
d) kinetics
Answer: a
Clarification: The study of inertia forces arising from the combined effect of the mass and motion of the parts is called kinetics.
The study of relative motion between the parts of a machine is called kinematics.
The study of the relative motion between the parts of a machine and the forces acting on the partsis called theory of machines.

4. The type of pair formed by two elements which are so connected that one is constrained to turn or revolve about a fixed axis of another element is known as
a) turning pair
b) rolling pair
c) sliding pair
d) spherical pair
Answer: a
Clarification: When two elements of a pair are connected in such a way that one can only turn or revolve about a fixed axis of another link, the pair is known as turning pair.

5. Which of the following is a lower pair?
a) ball and socket
b) piston and cylinder
c) cam and follower
d) both a and b
Answer: d
Clarification: In both ball and socket and piston cylinder there is surface contact between the two elements. Hence, they form a lower pair.

6. If two moving elements have surface contact in motion, such pair is known as
a) sliding pair
b) rolling pair
c) surface pair
d) lower pair
Answer: d
Clarification: when two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as lower pair.

7. The example of lower pair is
a) shaft revolving in a bearing
b) straight line motion mechanisms
c) automobile steering gear
d) all of the mentioned
Answer: d
Clarification: In all the mentioned elements there is surface contact between the two elements. Hence, they form a lower pair.

8. Pulley in a belt drive acts as
a) cylindrical pair
b) turning pair
c) rolling pair
d) sliding pair
Answer: c
Clarification: When the two elements of a pair are connected in such a way that one rolls over another fixed link, the pair is known as rolling pair. In belt and pulley, the belt rolls over the pulley.

9. The example of rolling pair is
a) bolt and nut
b) lead screw of a lathe
c) ball and socket joint
d) ball bearing and roller bearing
Answer: d
Clarification: In ball bearing and roller bearing one element rolls over the other element. Hence, they are examples of rolling pair.

10. Any point on a link connecting double slider crank chain will trace a
a) straight line
b) circle
c) ellipse
d) parabola
Answer: c
Clarification: One of the inversions of a double slider crank chain is elliptical trammels. So, from the above given options ellipse is best suited.

11. The purpose of a link is to
a) transmit motion
b) guide other links
c) act as a support
d) all of the mentioned
Answer: d
Clarification: None

12. A universal joint is an example of
a) higher pair
b) lower pair
c) rolling pair
d) sliding pair
Answer: b
Clarification: In universal joint, there is surface contact between the two elements. Hence, they form a lower pair.

13. Rectilinear motion of piston is converted into rotary by
a) cross head
b) slider crank
c) connecting rod
d) gudgeon pin
Answer: b
Clarification: In single slider crank chain rotary motion is converted into reciprocating motion.

250+ TOP MCQs on Simple Mechanisms – 2 and Answers

Machine Kinematics Interview Questions and Answers for Experienced people on “Simple Mechanisms – 2”.

1. The relation between the number of links (l) and the number of binary joints ( j) for a kinematic chain having constrained motion is given by j = 3/2 I -2 If the left hand side of this equation is greater than right hand side, then the chain is
a) locked chain
b) completely constrained chain
c) successfully constrained chain
d) incompletely constrained chain
Answer: a
Clarification: If the left hand side is greater than the right hand side, therefore it is not a kinematic chain and hence no relative motion is possible. Such type of chain is called locked chain and forms a rigid frame or structure which is used in bridges and trusses.

2. In a kinematic chain, a quaternary joint is equivalent to
a) one binary joint
b) two binary joints
c) three binary joints
d) four binary joints
Answer: c
Clarification: When four links are joined at the same connection, the joint is called a quaternary joint. It is equivalent to three binary joints.

3. If n links are connected at the same joint, the joint is equivalent to
a) (n – 1) binary joints
b) (n – 2) binary joints
c) (2n – 1) binary joints
d) none of the mentioned
Answer: a
Clarification: In general, when n number of links are joined at the same connection, the joint is equivalent to (n – 1) binary joints.

4. In a 4 – bar linkage, if the lengths of shortest, longest and the other two links are denoted by s, l, p and q, then it would result in Grashof’s linkage provided that
a) l + p < s + q
b) l + s < p + q
c) l + p = s + q
d) none of the mentioned
Answer: b
Clarification: None

5. A kinematic chain is known as a mechanism when
a) none of the links is fixed
b) one of the links is fixed
c) two of the links are fixed
d) all of the links are fixed
Answer: b
Clarification: When one of the links of a kinematic chain is fixed, the chain is known as mechanism. It may be used for transmitting or transforming motion e.g. engine indicators, typewriter etc.

6. The Grubler’s criterion for determining the degrees of freedom (n) of a mechanism having plane motion is
a) n = (l – 1) – j
b) n = 2 (l – 1) – 2j
c) n = 3 (l – 1) – 2j
d) n = 4 (l – 1) – 3j
Answer: c
Clarification: The Grubler’s criterion applies to mechanisms with only single degree of freedom joints where the overall movability of the mechanism is unity.
i.e. n = 3 (l – 1) – 2j
where l = Number of links, and j = Number of binary joints.

7. The mechanism forms a structure, when the number of degrees of freedom (n) is equal to
a) 0
b) 1
c) 2
d) – 1
Answer: a
Clarification: When n = 0, then the mechanism forms a structure and no relative motion between the links is possible.
When n = 1, then the mechanism can be driven by a single input motion.
When n = 2, then two separate input motions are necessary to produce constrained motion for the mechanism.
When n = – 1 or less, then there are redundant constraints in the chain and it forms a statically indeterminate structure.

8. In a four bar chain or quadric cycle chain
a) each of the four pairs is a turning pair
b) one is a turning pair and three are sliding pairs
c) three are turning pairs and one is sliding pair
d) each of the four pairs is a sliding pair.
Answer: a
Clarification: A very important consideration in designing a mechanism is to ensure that the input crank makes a complete revolution relative to the other links. The mechanism in which no link makes a complete revolution will not be useful. In a four bar chain, one of the links, in particular the shortest link, will make a complete revolution relative to the other three links, if it satisfies the Grashof ’s law. Such a link is known as crank or driver.

9. Which of the following is an inversion of single slider crank chain ?
a) Beam engine
b) Watt’s indicator mechanism
c) Elliptical trammels
d) Whitworth quick return motion mechanism
Answer: d
Clarification: None

10. Which of the following is an inversion of double slider crank chain ?
a) Coupling rod of a locomotive
b) Pendulum pump
c) Elliptical trammels
d) Oscillating cylinder engine
Answer: c
Clarification: A kinematic chain which consists of two turning pairs and two sliding pairs is known as double slider crank chain and elliptical trammels are such pairs.

250+ TOP MCQs on Single Slider Crank Chain and its Inversions – 2 and Answers

Tough Machine Kinematics Questions and Answers on “Single Slider Crank Chain and its Inversions – 2”.

1. A single slider crank chain is a _______
a) 4-link mechanism
b) 3-link mechanism
c) 2-link mechanism
d) 6-link mechanism
Answer: a
Clarification: A single slider crank chain is a four link mechanism, any four link mechanisms has 4 links inclusive of higher and lower pairs.

2. Bull engine is an inversion of single slider crank chain.
a) True
b) False
Answer: a
Clarification: In a bull engine the inversion is obtained by fixing the cylinder, thus it is an inversion of a single slider crank chain.

3. Find the ratio of the time of cutting to the time of return stroke from the following information: A crank and slotted lever mechanism used in a shaper has a centre distance of 0.300 m between the centre of oscillation of the slotted lever and the centre of rotation of the crank. The radius of the crank is 0.120 m.
a) 1.72
b) 1.65
c) 1.81
d) 1.79
Answer: a
Clarification: We know that time of cutting stroke to the time of return stroke is given by
360-α/ α
Using trigonometric ratios we find that α =132.8°
therefore, Ratio = 1.72.

4. Find the inclination of the slotted bar with the vertical in degrees in the extreme position from the following information: In a crank and slotted lever quick return motion mechanism, the distance between the fixed centres is 0.240 m and the length of the driving crank is 0.120 m.
a) 30
b) 45
c) 60
d) 75
Answer: a
Clarification: In a crank and slotted lever mechanism, symmetry can be observed. Using this symmetry and trigonometric ratios we find that
angle = 30 degrees.

5. Find the ratio of the time of cutting to the time of return stroke from the following information: In a crank and slotted lever quick return motion mechanism, the distance between the fixed centres is 0.240 m and the length of the driving crank is 0.120 m.
a) 3
b) 4.5
c) 3.2
d) 2
Answer: d
Clarification: In a crank and slotted lever mechanism, symmetry can be observed. Using this symmetry and trigonometric ratios we find that vertical inclination of slotted bar is
angle = 30 degrees.
now 90- α/2 = 30
α=120 degrees
therefore ratio = 2.

6. Find the length of stroke if the length of the slotted bar is 0.45m and LOS passes through the free end of the lever. Length of driving crank = 0.12m, distance between fixe centres = 0.24m. Crank and slotted lever quick return motion mechanism.
a) 450mm
b) 400mm
c) 500mm
d) 475mm
Answer: a
Clarification: We know that length of stroke is:
2x450xsin(90-α/2)
α=120 degrees,
therefore
length = 450mm.

7. Which of the following mechanism is mostly used in shaping and slotting machines?
a) Whitworth quick return motion mechanism
b) Bull engine
c) Crank and slotted lever quick return motion mechanism
d) Gnome engine
Answer: a
Clarification: Whitworth quick return motion mechanism is mostly used in shaping and slotting machines, as in this mechanism a turning pair is fixed and the driving crank rotates at a uniform speed.

8. In Whitworth quick return motion mechanism, the driving crank is under an accelerated motion
a) True
b) False
Answer: b
Clarification: In Whitworth quick return motion mechanism, the driving crank rotates at a uniform speed and is widely used in shaping and slotting machines.

9. Which of the following mechanism is used to convert reciprocating motion into rotary motion?
a) Whitworth quick return motion mechanism
b) Oscillating cylinder engine
c) Crank and slotted lever quick return motion mechanism
d) Gnome engine
Answer: a
Clarification: Oscillating cylinder engine is used to convert reciprocating motion into rotary motion, the piston reciprocates and the cylinder oscillates about the pin.

10. How many cylinders are there in Gnome engine?
a) 4
b) 5
c) 6
d) 7
Answer: d
Clarification: Rotary internal combustion engines were used in aviation. Now-a-days gas turbines are used in its place. It consists of seven cylinders in one plane and all revolves about fixed centre.

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250+ TOP MCQs on Straight Line Mechanism and Answers

Machine Kinematics Multiple Choice Questions on ” Straight Line Mechanism”.

1. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the maximum speed of the intermediate shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m
c) 566.25 r.p.m
d) 441.5 r.p.m.
Answer: a
Clarification: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
Maximum speed of the intermediate shaft,

NB(max) = NA/cosα = 500/cos 20°= 532.1 r.p.m.

2. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the minimum speed of the intermediate shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m.
c) 566.25 r.p.m.
d) 441.5 r.p.m.
Answer: b
Clarification: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
minimum speed of the intermediate shaft,

NB(min) = NAcosα = 500 × cos 20° = 469.85 r.p.m.

3. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the maximum speed of the driven shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m.
c) 566.25 r.p.m.
d) 441.5 r.p.m.
Answer: c
Clarification: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
Maximum speed of the driven shaft,

NC(max) = NB(max)/cosα = NA/cos2α = 566.25 r.p.m.

4. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the minimum speed of the driven shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m.
c) 566.25 r.p.m.
d) 441.5 r.p.m.
Answer: d
Clarification: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
minimum speed of the driven shaft,
NC(min) = NB(min)× cos α = NAcos2α = 441.5 r.p.m.

5. In a pantograph, all the pairs are
a) turning pairs
b) sliding pairs
c) spherical pairs
d) self-closed pairs
Answer: a
Clarification: In a pantograph, all the pairs are turning pairs. It has 4 links.

6. Which of the following mechanism is made up of turning pairs ?
a) Scott Russel’s mechanism
b) Peaucellier’s mechanism
c) Hart’s mechanism
d) Both (a) and (b)
Answer: d
Clarification: None.

7. Which of the following mechanism is used to enlarge or reduce the size of a drawing ?
a) Grasshopper mechanism
b) Watt mechanism
c) Pantograph
d) none of the mentioned
Answer: c
Clarification: A pantograph is an instrument used to reproduce to an enlarged or a reduced scale and as exactly as possible the path described by a given point.

8. The Ackerman steering gear mechanism is preferred to the Davis steering gear mechanism, because
a) whole of the mechanism in the Ackerman steering gear is on the back of the front wheels
b) the Ackerman steering gear consists of turning pairs
c) the Ackerman steering gear is most economical
d) both (a) and (b)
Answer: d
Clarification: The Ackerman steering gear mechanism is much simpler than Davis gear. The difference between the Ackerman and Davis steering gears are :
1. The whole mechanism of the Ackerman steering gear is on back of the front wheels; whereas in Davis steering gear, it is in front of the wheels.
2. The Ackerman steering gear consists of turning pairs, whereas Davis steering gear consists of sliding members.

9. The driving and driven shafts connected by a Hooke’s joint will have equal speeds, if
a) cos θ = sin α
b) sinθ = ±√tanα
c) tanθ = ±√cosα
d) cot θ = cos α
Answer: c
Clarification: None.

10. In a Davis steering gear, the distance between the pivots of the front axle is 1.2 metres and the wheel base is 2.7 metres. Find the inclination of the track arm to the longitudinal axis of the car, when it is moving along a straight path.
a) 12.5°
b) 13.5°
c) 14.5°
d) 15.5°
Answer: a
Clarification: c = 1.2 m ; b = 2.7 m
Let α = Inclination of the track arm to the longitudinal axis.
We know that tan α = c/2b = 1.2/2 x 2.7
or, α = 12.5°.

250+ TOP MCQs on Friction of Pivot and Collar Bearing and Answers

Machine Kinematics Multiple Choice Questions on “Friction of Pivot and Collar Bearing”.

1. The power from the engine to the rear axle of an automobile is transmitted by means of
a) worm and worm wheel
b) spur gears
c) bevel gears
d) hooke’s joint
Answer: d
Clarification: A Hooke’s joint is used to connect two shafts, which are intersecting at a small angle. In automobiles, the power is transmitted through this only.

2. A force acting in the opposite direction to the motion of the body is called force of friction.
a) True
b) False
Answer: a
Clarification: The force of friction always acts in a direction, opposite to that in which the body tends to move.

3. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
a) static friction
b) dynamic friction
c) limiting friction
d) coefficient of friction
Answer: c
Clarification: The friction, experienced by a body, when at rest, is known as static friction.
The friction, experienced by a body, when in motion, is known as dynamic friction.
The maximum frictional force, which comes into play, when a body just begins to slide over
the surface of the other body, is known as limiting friction.

4. The friction experienced by a body, when at rest, is known as static friction.
a) True
b) False
Answer: a
Clarification: The friction, experienced by a body, when at rest, is known as static friction.
The friction, experienced by a body, when in motion, is known as dynamic friction.
The maximum frictional force, which comes into play, when a body just begins to slide over
the surface of the other body, is known as limiting friction.

5. The dynamic friction is the friction experienced by a body, when the body
a) is in motion
b) is at rest
c) just begins to slide over the surface of the other body
d) none of the mentioned
Answer: a
Clarification: The friction, experienced by a body, when at rest, is known as static friction.
The friction, experienced by a body, when in motion, is known as dynamic friction.
The maximum frictional force, which comes into play, when a body just begins to slide over
the surface of the other body, is known as limiting friction.

6. The static friction
a) bears a constant ratio to the normal reaction between the two surfaces
b) is independent of the area of contact, between the two surfaces
c) always acts in a direction, opposite to that in which the body tends to move
d) all of the mentioned
Answer: d
Clarification: The laws of static friction are:
a) The force of friction always acts in a direction, opposite to that in which the body tends to move.
b) The magnitude of the force of friction is exactly equal to the force, which tends to move.
c) The force of friction is independent of the area of contact, between the two surfaces.
d) The force of friction depends upon the roughness of the surfaces.

7. Which of the following statements regarding laws governing the friction between dry surfaces are correct?
a) The friction force is dependent on the materials of the contact surfaces.
b) The friction force is directly proportional to the normal force.
c) The friction force is independent of the area of contact.
d) All of the mentioned
Answer: d
Clarification: The laws of friction between dry surfaces are:
a) The force of friction always acts in a direction, opposite to that in which the body tends to move.
b) The magnitude of the force of friction is exactly equal to the force, which tends to move.
c) The force of friction is independent of the area of contact, between the two surfaces.
d) The force of friction depends upon the roughness of the surfaces.

8. The angle of the inclined plane at which the body just begins to slide down the plane, is called helix angle.
a) True
b) False
Answer: b
Clarification: The angle of the inclined plane at which the body just begins to slide down the plane, is called angle of repose.

9. The angle which the normal reaction makes with the resultant reaction is called angle of friction.
a) True
b) False
Answer: a
Clarification: The angle of the inclined plane at which the body just begins to slide down the plane, is called angle of repose. The angle which the normal reaction makes with the resultant reaction is called angle of friction.

10. The angle of inclination of the plane, at which the body begins to move down the plane is called
a) angle of friction
b) angle of repose
c) angle of projection
d) none of the mentioned
Answer: b
Clarification: The angle of the inclined plane at which the body just begins to slide down the plane, is called angle of repose. The angle which the normal reaction makes with the resultant reaction is called angle of friction.