Successfully reported this slideshow.
Upcoming SlideShare
×

# THEORY OF MACHINES I QUESTION BANK

2,832 views

Published on

TOM-I QUESTION BANK UNIT 1-2

Published in: Engineering
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

### THEORY OF MACHINES I QUESTION BANK

1. 1. UNIT-I A] Theory Question Bank Q. No Description 1 Define the following terms : (i) Kinematic chain (ii) Structure (iii) Kinematic pair (iv)Degree of freedom in Mechanism. 2 Define inversion of a mechanism. Explain with the help of neat sketches inversions of double slider crank chain. Give their applications. 3 Calculate the number of degree of freedom of the mechanism As shown 4 Explain the following terms with suitable examples : (i) Completely constrained motion (ii) Incompletely constrained motion (iii) Successfully constrained motion. 5 Explain with neat sketches ‘Swinging and Rocking Mechanisms’. 6 What is the condition for correct steering? Explain with neat sketch Ackermann steering gear mechanism. 7 Describe the three kinds of lower pairs, giving a sketch of each kind, and state the types of relative
2. 2. motion that each pair permits. 8 Explain with a neat sketch ‘Geneva Mechanism’. 9 Fill in the blanks with correct alternative and rewrite the complete sentences : (i) Oldham’s coupling is the inversion of.............................. . (a) Four bar mechanism (b) Crank and lever mechanism (c) Single slider crank mechanism (d) Double slider crank mechanism (ii) ..........................number of pairs are associated with quaternary joint. (a) 1 (b) 2 (c) 3 (d) 4 (iii) A combination of kinematic pairs, joined in such a way that the relative motion between the links is completely constrained, is called a........................... (a) Structure (b) Mechanism (c) Kinematic Chain (d) Inversion 10 What is meant by a ‘steering gear mechanism’? Why is it necessary? Why are steering gear mechanisms
3. 3. seen in four wheelers and not in two or three- wheelers? Explain 11 Define the Following Term i) Grashoff’s Law ii) Structure iii) Degree of Freedom iv) Mechanism 12 Explain with neat sketch whitworth Quick Return Mechanism 13 What is a condition of correct steering? With the help of neat sketch explain the construction and working of Davis Steering Gear mechanism 14 Define the following i) Machine ii) Kinematic Chain iii) Kinematic Link iv] Grashoff’s law 15 Explain the following terms with suitable examples:- i] Completely constrained motion ii] Incompletely constrained motion iii] Successfully constrained motion 16 Write short note on i) Pantograph along with its application. ii) Scotch yoke mechanism 17 In a Oldham coupling, the distance between shaft axes is 30 mm and speed of rotation is 600 rpm, what is maximum speed of sliding of each tongue in the slot?
4. 4. 18 Define:- 1. DOF of a body 2. DOF of a mechanism 19 Define and explain with neat sketches the various types of constrained motions 20 Define kinematic pair and discuss various types of kinematic pairs with examples. 21 State and explain Grubler criterion for mobility of a planer mechanism with various applications using lower pairs and higher pairs 22 Different mechanisms may be obtained by inversions of the same kinematic chain. Explain the meaning of this statement with all inversions of single slider crank chain. Give practical application of each inversion 23 With the help of neat sketch, explain Pecullier straight line mechanism giving proof of the tracing point describing exact straight line 24 Explain the working of Davis steering gear with the help of a neat sketch. Find the inclination of track arm in terms of wheel base and the distance between the pivots of the axle in order to satisfy the condition of steering. 25 Write short note on “Ackermann steering gear” 26 In a Davis steering gear the distance between the pivots of the front axle is 120 cm and the wheel base is 260 cm. When the vehicle is moving on a straight path, find the inclination of track arms to the vertical 27 A car using Ackermann steering gear has a wheel
5. 5. base of 2.8m and a track of 1.5m. The track rod is 1.1m and the track arm is 0.15m. The distance between the pivots of stub axle is 1.2m. Find the radius of turning of inner wheels for correct steering. 28 Write a short note on elliptical trammel. State and explain the condition for which it will trace a circle 29 In case of an elliptical trammel, prove that any point on the coupler rod traces perfect ellipse. Hence locate that point on the coupler, which will trace circle 30 Write a short note on Gnome engine 31 Compare ‘Davis’ and ‘Ackermann’ steering gear mechanisms 32 In the Davis steering gear mechanism, the distance between the pivots of the front axles is 1.2m. The wheel base is 3m. When a vehicle is moving along a straight path, find the inclination of the track arms to the longitudinal axis, provided that the mechanism has to satisfy the condition of correct steering 33 In case of Davis steering gear mechanism: 1. The distance between the pivots of the front axle = 1.5m 2. The wheel base = 5m Find the inclination of the track arms to the longitudinal axis, provided that the mechanism has
6. 6. to satisfy the condition of correct steering 34 What is kinematic pair? Give its classification in details. 35 Explain types of kinematic links with neat sketches 36 Explain types of kinematic joints with neat sketches 37 Explain Kutzbach criterion. 38 Differentiate between Machine and Mechanism 39 What is four bar chain mechanism? Explain any one Inversion with neat sketch 40 Explain Beam engine with neat sketch 41 Explain Fourth Inversion of Single slider crank mechanism with neat sketch 42 Explain Skotch yoke mechanism with neat sketch 43 Write a short note on Equivalent linkage of mechanism 44 Calculate the number of degree of freedom of the mechanism As shown in Fig 45 Calculate the number of degree of freedom of the
7. 7. mechanism As shown in Fig 46 Calculate the number of degree of freedom of the mechanism As shown 47 Calculate the number of degree of freedom of the mechanism As shown 48 Calculate the number of degree of freedom of the mechanism As shown
8. 8. 49 Calculate the number of degree of freedom of the mechanism As shown 50 What are rigid and resistant bodies? Elaborate.
9. 9. MCQ QUESTION BANK Q. No Description 1 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 Ans. (c) when ‘l ’ number of links are joined at the same connection, the joint is equivalent to (L - 1) binary joints 2 A round bar A passes through the cylindrical hole in B as shown in the given figure. Which one of the following statements is correct in this regard? a) The two links shown form a kinematic pair. b) The pair is completely constrained. c) The pair has incomplete constraint. d) The pair is successfully constrained. Ans. (c) 3 Consider the following statements 1. A round bar in a round hole form a turning pair. 2. A square bar in a square hole forms a sliding pair. 3. A vertical shaft in a footstep bearing forms a successful constraint. Of these statements (a) 1 and 2 are correct
10. 10. (b) 2 and 3 are correct (c) 1 and 3 are correct (d) 1, 2 and 3 are correct Ans. (b) 4 Consider the following statements: 1. Lower pairs are more resistant than the higher pairs in a plane mechanism. 2. In a 4-bar mechanism (with 4 turning pairs), when the link opposite to the shortest link is fixed, a double rocker mechanism results. Which of the statements given above is/are correct? (a) Only 1 (b) Only 2 (c) Both 1 and 2 (d) Neither 1 nor 2 Ans. (c) 5 Consider the following pairs of parts: 1. Pair of gear in mesh 2. Belt and pulley 3. Cylinder and piston 4. Cam and follower Among these, the higher pairs are (a) 1 and 4 (b) 2 and 4 (c) 1, 2 and 3 (d) 1, 2 and 4 Ans. (a) 6 Which of the following is a higher pair? (a) Belt and pulley (b) Turning pair (c) Screw pair (d) Sliding pair Ans. (a) A higher pair have point or line contact. 7 Which of the following disciplines provides study of relative motion between the parts of a machine (a) theory of machines (b) applied mechanics (c)mechanisms (d) kinetics (e) kinematics Ans: e
11. 11. 8 Which of the following is a lower pair (a) ball and socket (b) piston and cylinder (c) cam and follower (d) (a) and (b) above (e) belt drive. Ans: d 9 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 (e) higher pair. Ans: e 10 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 above (e)none of the above. Ans: d 11 Pulley in a belt drive acts as (a)cylindrical pair (b)turning pair (c) rolling pair (d)sliding pair (e)surface pair. Ans: c 12 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 (e) all of the above. Ans: d 13 A universal joint is an example of (a)higher pair (b)lower pair (c)rolling pair (d)sliding pair (e)turning pair.
12. 12. Ans: b 14 The example of spherical pair is (a)bolt and nut (b)lead screw of a lathe (c)ball and socket joint (d)ball bearing and roller bearing (e)none of the above. Ans: c 15 Cross head and guides form a (a)lower pair (b)higher pair (c)turning pair (d)rolling pair (e)sliding pair. Ans: e 16 If there are L number of links in a mechanism then number of possible inversions is equal to (a)L+1 (b)L-1 (c)L (d)L+2 (e)L-2. Ans: c 17 The lower pair is a (a)open pair (b)closed pair (c)sliding pair (d)point contact pair (e)does not exist. Ans: b 18 Which of the following would constitute a link (a)piston, piston rings and gudgeon pin (b)piston, and piston rod (c)piston rod and cross head (d)piston, crank pin and crank shaft (e)piston, piston-rod and cross head. Ans:e 19 Ackermann steering gear consists of (a)sliding pairs
13. 13. (b)turning pairs (c)rolling pairs (d)higher pairs (e)lower pairs. Ans: b 20 Oldham's coupling is the (a)second inversion of double slider crank chain (b)third inversion of double slider crank chain (c)second inversion of single slider crank chain (d)third inversion of slider crank chain (e)fourth inversion of double slider crank chain. Ans: b 21 The number of links in pantograph mechanism is equal to (a) 2 (b) 3 (c) 4 (d) 5 (e) 6. Ans:c 22 Rectangular bar in a rectangular hole is the following type of pair (a)completely constrained motion (b) partially constrained motion (c) incompletely constrained motion (d) freely constrained motion (e) none of the above. Ans: a 23 Governor is used in automobile to (a)decrease the variation of speed (b)to control
14. 14. (c)to control SN (d)all of the above (e)none of the above. Ans: c 24 Idler pulley is used (a)for changing the direction of motion of the belt (b)for applying tension (c)for increasing -velocity ratio (d)all of the above (e)none of the above. Ans: b 25 The locus of a point on a thread unwound from a cylinder will be (a) a straight line (b) a circle (c) involute (d) cycloid (e) helix. Ans: c 26 Throw of a cam is the maximum distance of the follower from (a)base circle (b)pitch circle (c)root circle (d)prime circle (e)inner circle. Ans: a 27 Kinematic pairs are those which have (a)point or line contact between the two elements when in motion (b)surface contact between the two elements when in motion (c)elements of pairs not held together mechanically
16. 16. Ans: b 32 The main disadvantage of the sliding pair is that it is (a)bulky (b)wears rapidly (c)difficult to manufacture (d)(a) and (b) above (e)(a) and (c) above. Ans: d 33 A kinematic chain requires at least (a)2 links and 3 turning pairs (b)3 links and 4 turning pairs (c)4 links and 4 turning pairs (d)5 links and 4 turning pairs (e)none of the above. Ans: c 34 Kinematic pairs are those which have (a)two elements held together mechanically (b)two elements having relative motion (c)two elements having Coroili's component (d)minimum of two instantaneous centers (e)all of the above. Ans: b 35 A ball and socket joint form a a.turning pair b.rolling pair c.sliding pair d.spherical pair answer :- d.spherical pair 36 If a kinematic chain has 'l' links, then the number of
17. 17. mechanism obtained are a. l - 1 b. l - 2 c. l+1 d. l answer :- d.l 37 A rigid body possesses_____degrees of freedom. a. One b. Two c. Four d. Six (Ans:d) 38 Which of the following is an open pair? a. Journal bearing b. Ball and Socket joint c. Leave screw and nut d. None of the above (Ans:c) 39 . ________ is an inversion of Double slider crank chain. a. Coupling rod of a locomotive b. Scotch yoke mechanism c. Hand pump d. Reciprocating engine (Ans:b) 40 The Kutzbach criterion for determining the number of degrees of freedom (n) is (where l = number of links, j = number of joints and h = number of higher pairs) a. n = 3(l-1)-2j-h b. n = 2(l-1)-2j-h c. n = 3(l-1)-3j-h d. n = 2(l-1)-3j-h (Ans:a)
18. 18. 41 What is the number of instantaneous centres for an eight link mechanism? a. 15 b. 28 c. 30 d. 8 (Ans:b) 42 Consider the following mechanisms: 1. Oscillating cylinder engine mechanism 2. Toggle mechanism 3. Radial cylinder engine mechanism 4. Quick return mechanism Which of the above are inversions of slider crank mechanism? 1. 1, 2 and 4 2. 2, 3 and 4 3. 1, 2 and 3 4. 1, 3 and 4 (Ans: d) 43 The kinematic chain shown in the above figure is a (a) structure (b) mechanism with one degree of freedom (c) mechanism with two degree of freedom (d)mechanism with more than two degrees of freedom
19. 19. Ans. (d) 44 In the given figure, ABCD is a four-bar mechanism. At the instant shown, AB and CD are vertical and BC is horizontal AB is shorter than CD by 30 cm. AB is rotating at 5 radius and CD is rotating at 2 rad/s. The length of AB is (a) 10cm (b) 20 cm (c) 30 cm (d) 50 cm Ans. (b) 5L=2(L+30), 3L=60, L=20 45 In a single slider four-bar linkage, when the slider is fixed, it forms a mechanism of (a) hand pump (b) reciprocating engine (c) quick return (d) oscil1ating cylinder Ans. (a) 46 The type of quick return mechanism employed mostly in shaping machines is: (a) DC reversible motor (b) Fast and loose pulleys(c) Whitworth motion (d) Slotted link mechanism
20. 20. Ans. (d) 47 The Whitworth quick return mechanism is formed in a slider- crank chain when the (a) coupler link is fixed (b) longest link is a fixed link(c) slider is a fixed link (d) smallest link is a fixed link Ans. (d) 48 ABCD is a mechanism with link lengths AB = 200, BC = 300, CD = 400 and DA =350. Which one of the following links should be fixed for the resulting mechanism to be a double crank mechanism? (All lengths are in mm) a)A B (b) BC (c) CD (d) DA Ans. (c) 49 Scotch yoke mechanism is used to generate (a) sine functions (b) square roots (c) logarithms (d) inversions Ans. (a) 50 Which one of the following is an exact straight line mechanism using lower pairs? (a) Watt's mechanism (b) Grasshopper mechanism (c) Robert's mechanism (d) Paucellier’s mechanism
21. 21. Ans. (d)
22. 22. UNIT-II A] Theory Question Bank Q. No Description 01 Explain the difference between static and dynamic force analysis 02 Explain the following i) Inertia ii) D’Alembert’s Principle iii)SHM iv) Radius of Gyration 03 What is the difference between simple pendulum and compound pendulum 04 Derive relation for periodic time of oscillation of a connecting rod (Compound Pendulum) 05 Derive relation for periodic time of oscillation of a bar when it is suspended by two long strings attached at its ends (Bifilar Suspension) 06 Derive relation for periodic time of oscillation of a circular disc when it is suspended by three long strings attached at its periphery (Trifilar Suspension) 07 Explain the concept of Dynamically (or Kinetically) Equivalent System 08 Sometimes why it is required to have ‘Correction Couple’ for two mass dynamically equivalent system 09 How to calculate ‘Correction Couple’ for two mass dynamically equivalent system 10 Neglecting Inertia force derive a relation for Piston Side Thrust
23. 23. 11 Neglecting Inertia force derive a relation for Tangential force acting on crank pin 12 Considering the Inertia Forces derive a relation for Torque exerted on the crank shaft due to inertia forces 13 Considering the Inertia Forces derive a relation for Torque exerted on the crank shaft due to correction couple 14 Considering the Inertia Forces derive a relation for Torque exerted on the crank shaft due to weight of mass m2 at big end centre 15 Explain T-θ diagram for a single cylinder four stroke IC Engine 16 Describe Types of Friction 17 Describe Laws of Dry Friction 18 Derive a relation for Limiting angle of Friction 19 Describe Friction in Turning Pairs 20 Describe Friction Circle 21 Describe Friction Axis of a Link 22 Explain friction circle. Deduce an expression for the radius of friction circle in terms of the journal and the angle of friction. 23 Compare compound pendulum and bifilar pendulum suspension method of finding the mass moment of inertia of rod like body. 24 Draw and explain turning moment diagram of a 4 stroke cylinder Engine. State significance of it 25 A connecting rod of mass of 3.5 kg is suspended by two wires each of 2 m length. The wires are attached to the rod at points 150 mm on either side of the centre of gravity. if the connecting rod makes 35 oscillations in 60 seconds. Find the radius of gyration and the mass moment of inertia of the connecting rod about its centre of gravity. 26 A machine component of mass 5 kg is placed on a rectangular horizontal platform which is suspended by two equal strings of length 1.25 mm from rigid support and equidistance of 125 from C.G.
25. 25. located at the small end centre, (ii)the correction couple, if two masses are placed at the two ends and the angular acceleration of the connecting rod is 20,000 rad/s2anticlockwise 31 A high speed vertical engine has a connecting rod length five times the crank which is 60 mm. Its mass is 3 kg and has a C.G. 200mm from the small end bearing. When suspended in a small end bearing, it makes 50 oscillations in 52 seconds. The reciprocating parts have a mass of 1.5 kg. Determine the torque exerted on the crankshaft due to inertia of the moving parts when the crank makes an angle of 135º with TDC, and speed of rotation is 1200 rpm 32 A single cylinder horizontal steam engine has a stroke of 0.75 m and a connecting rod 1.8 m long. The mass of reciprocating parts is 520 kg and that of the connecting rod is 230 kg. Centre of gravity of the connecting rod is 0.8 m from crank pin and the moment of inertia about an axis through the centre of gravity perpendicular to the plane of motion is 100 kg.m2 . For an engine speed of 90 rpm and a crank position of 45° from the IDC, determine the torque on the crankshaft due to the inertia of these parts by analytical method 33 A connecting rod is suspended from a point 25 mm above the small end centre and 650 mm above its C.G. It makes 20 oscillations in 35 seconds. Find dynamically equivalent two masses when one mass is placed at small end centre. Take mass of connecting rod as 40 kg 34 A rigid link 500 mm long, mass 2 kg and radius of gyration 200 mm .replace this link by dynamically equivalent system of two masses located at the ends of the link. 35 Explain dynamic equivalence of two mass systems, for a connecting rod of an IC engine having mass ‘m’ and radius of gyration ‘k’. Obtain
26. 26. a two mass dynamically equivalent system, having one of the two masses at the small end. How dynamical equivalence is achieved if it is required that the other mass located at the big end 36 An IC engine has a stroke of 100 mm and bore of 80 mm. The connecting rod is 160 mm between centers and has total mass of 1.3 kg. Its center of mass is 130 mm away from small end center and radius of gyration about the mass center is 75 mm. The reciprocating mass is 1.8 kg. Determine magnitude of resultant forces on the crank pin, neglecting friction and gravity, when the crank is 300 after the TDC position and rotating at 1600 rpm clockwise. The gas pressure on the piston is 2 N/mm2 37 The connecting rod of an engine has length equal to 200 mm between centers and has mass equal to 3.5 kg. Its CG is at 80 mm from the big end centre and the radius of gyration about an axis through CG is 100 mm. Determine : (i) The two mass dynamically equivalent system when one mass is placed at the small end. (ii) The correction couple if two masses are placed at the two ends and angular acceleration of connecting rod is 100 rad/s2 clockwise. 38 The connecting rod of a vertical reciprocating engine is 2000 mm long between centres and its weights 250 kg. The mass centre is 800 mm from the big end centre. When it suspended as a pendulum from the small end axis, it makes 8 complete oscillations in 22 seconds. The crank is 400 mm long and rotates at 200 rpm. Determine by analytical method : (i) The mass moment of inertia of connecting rod about an axis through as mass centre. (ii) The inertia torque exerted on the crank shaft, when the crank has turned through 40° from the top dead centre and piston is moving downwards.
27. 27. 39 A connecting rod is suspended from a point 25 mm above the centre of small end, and 650 mm above its centre of gravity, its mass being 37.5 kg. When permitted to oscillate, the time period is found to be 1.87 seconds. Find the dynamical equivalent system constituted of two masses, one of which is located at the small end centre. 40 A vertical engine running at 1200 r.p.m. with a stroke of 110 mm has a connecting rod 250 mm between centers and mass 1.25 kg. The mass centre of the connecting rod is 75 mm from the big end centre and when suspended as pendulum from the gudgeon pin axis makes 21 complete oscillations in 20 seconds : (i) Calculate the radius of gyration of the connecting rod about an axis through its mass centre. (ii) When the crank is at 40º from the top dead centre and the piston is moving downwards, find analytically, the acceleration of the piston and the angular acceleration of the connecting rod. Hence find the inertia torque exerted on the crankshaft. To make the two- mass system to be dynamically equivalent to the connecting rod, necessary correction torque has to be applied and since the engine is vertical gravity effects are to be considered. 41 The connecting rod of an engine has a length equal to 220 mm between centers and has a mass equal to 2 kg. Its centre of gravity is at 150 mm from the small end centre and the moment of inertia of 0.02 kg-m2about its centre of gravity. Find : (I) the two mass dynamically equivalent system when one mass is located at the small end centre, (II) The correction couple, if two masses are placed at the two ends and the angular acceleration of the connecting rod is 20,000 rad/s2anticlockwise.
28. 28. 42 Explain dynamic equivalence of two mass systems, for a connecting rod of an IC engine having mass ‘m’ and radius of gyration ‘k’. Obtain a two mass dynamically equivalent system, having one of the two masses at the small end. How dynamical equivalence is achieved if it is required that the other mass located at the big. 43 The following data refers to horizontal reciprocating engine: Mass of reciprocating parts = 100 Kg, Stroke Length = 200 mm, Speed of engine = 900 rpm clockwise, Connecting rod mass = 80 Kg. Length between centers = 400 mm, Distance of C.G. from end center = 160 mm, Radius of gyration of connecting rod about an axis through C.G = 120 mm. Determine analytically the inertia torque on crankshaft when the crank has turned 400 from I.D.C 44 The following data refers connecting rod of a reciprocating engine: Mass = 55 Kg, Diameter of the small end bearing= 75 mm Diameter of the big end bearing= 100 mm Distance between bearing centers = 850 mm, Time of oscillation when the connecting rod is suspended from small end 1.83 seconds. Time of oscillation when the connecting rod is suspended from big end 1.68 second. Determine 1) The radius of gyration of connecting rod about an axis through C.G and perpendicular to the plane of oscillation 2) The moment of inertia of the rod about the same axis.
29. 29. 45 The piston diameter of an internal combustion engine is 125Mm and the stroke is 220 mm. The connecting rod is 4.5 times the crank length and has a mass of 50 kg. The mass of the reciprocating parts is 30 kg. The centre of mass of connecting rod is 170 mm from the crank pin centre and the radius of gyration about an axis through the centre of mass is 148 mm. The engine runs at 320 rpm. Find the magnitude and the direction of the inertia force and the corresponding torque on the crankshaft when the angle turned by the crank is 140º from the inner dead centre. 46 A gear of mass 4.5 kg is placed on a horizontal circular platform whose mass is 2.5 kg. it is suspended by three equal wires, each 1.5 m long ,from a rigid support .the wires are equally spaced round the circumference of a circle of 110 mm radius .when the C.G. of the gear coincides with the axis of the circular platform ,the platform makes 12 angular oscillations in 30 seconds .determine the mass moment of inertia of combined system about an axis through its C.G. 47 A rectangular cross section bar is suspended horizontally with the help of two equal strings equidistance from C.G. the length o0f each string is 300 mm and the distance between is each string and C.G. of the bar is 175 mm. the bar cross section is 30 mm x 20 mm and the length of the bar is 700 mm. the bar mass density is 7.8 gm / cc . Two identical cylindrical components each with mass 300 gm are kept on the bar on either sides of the C.G. of the bar. The distance between C. G. of the bar and the C. G. of the component is 225 mm. The bar together with the components is made to oscillate in the horizontal plane about the C. G. of the bar. The number of oscillations is 90 in 150 seconds. Assuming amplitude of oscillations as small calculate radius of gyration of the cylindrical components about the C. G. 48 In a slider crank mechanism, the crank is 200 mm long and
30. 30. connecting rod is 750 mm long. The piston is 80 mm in diameter and a pressure difference of 2 MPa exists between two sides of piston when the crank is moved through 45 degrees from top dead centre position find i) Thrust in connecting rod ii) Reaction from guide iii)Torque active on crank shaft iv) Load on main bearings 49 The mass of reciprocating parts of a steam engine is 225 kg. Diameter of the cylinder is 400 mm. Length of the Stroke is 500 mm and the ration of the connecting rod to crank is 4.2 When the crank is at inner dead centre, the difference in the pressure of the two sides of the piston is 5 bar. At what speed must the engine should run so that the thrust in the connecting rod in this position is equal to 5200 N 50 The obliquity ratio of a vertical reciprocating engine is 4.5 The engine bore and stroke is 75 mm and 90 mm respectively. The mass of the reciprocating parts is 1.2 kg. The gas pressure intensity is 5.5 bar when it has moved through 50 degrees from the i. d. c. on its power stroke. Determine: i) Piston Effort ii) Net load on gudgeon pin and crank pin iii)Thrust in cylinder walls iv) Thrust on the crank bearing Assuming speed of the engine as 2200 rpm. Calculate at what speed the load on gudgeon pin and the crank pin be zero. MCQ
31. 31. Q. No Description 1 4. The angle which the normal reaction makes with the resultant reaction is called …... A. normal angle B. angle of friction C. coff. of friction D. None of the above Answer- B 2 15. A body of weight W is required to move up the rough inclined plane whose angle of inclination with the horizontal is α. The effort applied parallel to the plane is given by (where μ = tan φ = Coefficient of friction between the plane and the body) A. P = W tan α B. P = W tan (α + φ) C. P = W (sin α + μ cos α) D. P = W (cos α + μ sin α) Answer: C 3 The essential condition of placing
32. 32. the two masses, so that the system becomes dynamically equivalent, is (where l1 and l2 = Distance of two masses from the centre of gravity of the body, and kG = Radius of gyration of the body) A.l1 = kG B.l2 = kG C.l1l2 = kG D.l1l2 = kG 2 Answer: D 4 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 me area of contact. D.all of the above Answer: D 5 The length of a simple pendulum
33. 33. which gives the same frequency as the compound pendulum, is A.kG + l1 B.kG 2 + l1 C. D. Answer: C 6 The friction experienced by a body, when at rest, is known as….. A. static friction B. Dynamic friction C. Both A &B D. None of the above Answer: A 7 The inertia force is equal to the …….in magnitude, but opposite in direction. A.Accelerating force B.Velocity C. Mass moment of inertia D.All of the above
34. 34. Answer: A 8 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 me area of contact. D.all of the above Answer: D 9 The acceleration of the particle moving with simple harmonic motion from the mean position is. A. Inversely proportional to the displacement of the particle B.Directly proportional to the displacement of the particle. C.Directly proportional to frictional force
35. 35. D. All of the above Answer: B 10 When a body moves with simple harmonic motion, the product of its periodic time and frequency is equal to A. zero B. one C. π/2 D. π Answer: B 11. The minimum force required to slide a body of weight W on a rough horizontal plane is A. W sin θ B. W cos θ C. W tan θ D. W cosec θ
36. 36. Answer: A 12 Correction couple is applied when --- A. If the Distance of m2 mass is selected arbitrarily B. If the Distance of m1 mass is selected arbitrarily C. Both masses m1 & m2 have to be selected arbitrarily D. All of the above Answer- C 13 While analyzing the inertia effect of connecting rod of slider crank mechanisms ,mass m1 is placed at small end which is – A.PISTON SIDE B.Crank side C. Both A & B D.None of the above Answer - A 14 The connecting rod of an engine has a length equal to 25cm between centers and has a mass equal to 3 kg. Its centre of gravity is at 175 mm from the small end centre and the moment of inertia of 0.025 kg-m2about its centre of gravity. when any one mass is located at small end, position of the second mass for dynamically equivalent system is …mm
37. 37. A. 55.2 B. 33.8 C. C.65.9 D. 47.6 Answer – D 15 In static force analysis Fp.tanφ is the equation of force A.gas force on piston B. piston side thrust C. piston effort D. inertia force due to piston Answer- B 16 In a slider crank mechanism, The crank is 0.3 m long and connecting rod is 0.85 m long .the piston is of 9 cm in diameter and gas pressure acting on the piston is 5Mpa .the piston effort is …..KN. A.45.78 B. 31.81 C.83.19 D. 19.10 Answer- B 17 In case of ……engine the effort of weight of reciprocating parts is also considered. A. Vertical B. Horizontal
38. 38. C. Both A &B D. None of the above. Answer- A 18 Normal reaction acting on the cylinder wall is also called as A. Piston side thrust B. Piston effort C.Net axial force on piston D. None of the above Answer- A 19 Radial force acting on crank shaft is also called as … A. Torque on the crank B. Radial force acting on the crank C. Tangential force on the crank D. All of the above Answer- C 20 Turning moment diagram is also called as… A.T-θ diagram B. Crank effort diagram C. Stress-strain diagram D. Both A&B Answer- D
39. 39. 21 When T-θ diagram is positive, the crankshaft …… A. Accelerates B. Retards C. Constant D. Linear Answer- B 22 In case of three cylinder engine the crank placed at …..to each other. A.00 B.900 C.1200 D.2700 Answer- C 23 In case of horizontal engine ,if the crank makes an angle of 1400 and rotates clockwise with IDC then torque due to mass at big end is A. Anticlockwise B. Clockwise C. Both A&B D. None of the above Answer- B 24 A shaft of radius 50 mm rotates in a bearing. If the coefficient of friction µ=0.25,then the radius of friction circle is -----
40. 40. A. 0.025 m B. 0.075 m C. 0.0955m D. 0.0125 m Answer- D 25 A shaft of radius 75 mm rotates in a bearing at 400 rpm. IF µ=0.35, then the diameter of friction circle is -----cm A. 10.00 B. 10.50 C. 2.12 D. 5.25 Answer- D 26 Friction torque is T= ----- A. P x (r/µ) B. P x (r.µ) C. P x (r-µ) D. All of the above Answer- B 27 Journal is also called as --- A. Hub B. Coupling C. Bearing D. Shaft Answer- D
41. 41. 28 A 300 N force is required to pull the body resting on a horizontal plane .the force is inclined at an angle of 300 with horizontal. If µ=0.1332, then the mass of the body is -----kg. A.214.5 B. 500 C.144.29 D.125.3 Answer- A 29 Sliding friction is the type of ----friction A. Film Friction B. Greasy Friction C. Dry Friction D. Kinematic Or Dynamic Friction Answer-C 30 MMI of a pulley is found by using ----method A. Simple pendulum B. Bifilar suspension C. Trifilar suspension D. Compound pendulum Answer-C 31 Time period of oscillations of torsional pendulum does not depend on --- A. Length of each wire