Question Bank - Mechanics of Machines.doc

KARPAGA VINAYAGA COLLEGE OF ENGINEERING AND TECHNOLOGY DEPARTMENT OF AUTOMOBILE ENGINEERING

DEGREE / BRANCH : B.E. / AUTOMOBILE ENGINEERING YEAR / SEMESTER : II / III NAME OF THE STAFF: Mr. M.MURUGESAN SUBJECT CODE : AE 2201 SUBJECT NAME: Mechanics of Machines

Question Bank

UNIT-1MECHANISMS

PART- A

1. Define ‘Degree of freedom’ or what is meant by mobility?2. Define kinematic chain. (AU Nov /Dec 2005)3. What is meant by spatial mechanism4. Classify constraint motion.5. What is a machine? Give two examples. (AU April/May 2005)6. What is the important application of single slider crank mechanism?7. Differentiate completely constrained motion and successfully constrained

motion with an example.8. Compare machine and structure.(AU Oct/Nov 2002) 9. Give example for kinematics pairs.

10. Define lower pair and higher pair; give two examples for each pair. (AU Nov /Dec 2005)

11. Different between kinematic pair and kinematic chain. 12. Compare movability and mobility. (AU April/May 2005)13. How many inversions are possible from a four bar kinematic chain? Name

them based on their input output motion. (AU April/May 2003) 14. Define inversion of mechanism. (AU May/June 2006)15. What is meant by transmission angle?16. What is mechanical advantage in a mechanism?17. What are the three conditions to obtain a four bar crank rocker

mechanism? (AU April/May 2003)18. State the Kutzback criterion.19. State grubler’s Criteria.20. Discuss machine and mechanism.21. State the grashof’s law for four bar mechanism.

PART- B

1. Sketch and explain any three kinematic inversion of a single slider crank chain (AU May/June 2006)

2. Explain the inversion mechanism of four bar chain?

Mechanics of Machines Page 1/12

3. Explain the inversion of single slider crank mechanism? (AU May/June 2006)

4. Explain the scotch yoke mechanism. (AU April/May 2005)

5. Explain the effect of transmission angle on mechanical advantage?

6. In the toggle mechanism, as shown in fig. the slider D is constrained to move on a horizontal path. The crank OA is rotating in the counter clockwise direction at a speed of 180rpm. The dimensions of various links as follows, OA=180mm, CB=240mm, AB=360mm, and BD=540mm.For the given configuration, find velocity of slider D, Angular velocity of the links AB, CB and BD. Velocity of rubbing on the pins of diameter 30mm at A and D.

7. PQRS is a four bar chain with link PS fixed. The length of the links are PQ=62.5mm, QR=175mm, RS=112.5mm, and PS=200mm. the crank PQ rotates at 10red/sec clockwise. Draw the velocity and acceleration diagram when angle QPS=60 and Q and R lie on the same side of PS. Find the angular velocity and angular acceleration of links QR and RS. (AU April/May 2005)

8. In a four bar mechanism ABCD, the link length in mm are as follows: input AB=25, coupler BC=85, output CD=50 and AD=60mm. The angle between the frame and the input is 100 measured anti-clockwise. The velocity of point B is 1.25 m/sec in the clockwise direction. Sketch the mechanism and determine the velocity and acceleration of the mid-point of the link BC. Also find the angular velocity and angular acceleration of the link BC and CD.

9. In a four bar link, mechanism the crank AB rotates at 36rad/sec. the length of the link are AB=200mm, BC=400mm, CD=450mm and AD=600mm. AD is the fixed link. At the instant when AB is at right angle to AD. Determine the velocity of (i) the midpoint of link BC. (ii) a point on link CD, 100mm from the point connecting the links CD and AD. (AU May/June 2006)

10. In a slider crank mechanism, the length of crank OB and connecting rod AB are 125mm and 500mm respectively. The center of gravity G of the connecting rod is 275mm from the slider A. the crank speed is 600rpm clockwise. When the crank has turned 45 from the inner dead center position, determine (i) velocity of the slider A, (ii) velocity of the point G. (iii) angular velocity of the connecting rod AB. (AU May/June 2006) (AU April/May 2005)

UNIT – II


FRICTIONPART-A

1. What is meant by slope of a thread?2. Define co-efficient of friction.3. Why self locking screws have lesser efficiency?4. Obtain the expression for length of an open belt drive. (AU Nov /Dec 2004)5. What are the functions of clutches?6. What are the difference between cone clutch and centrifugal clutch?7. Compare plate clutches and cone clutches.8. Why friction is called as necessary evil?9. What are the types of belt drives? (AU April/May 2004)

10. Define mechanical efficiency of screw and nut assembly. (AU May/June 2006)

11. Explain velocity ratio.12. State the law of belting.13. What is meant by angle of contact? (Lab angle)14. What is the centrifugal effect on belt?15. What are the disadvantages of V-belt drive over flat belt? (AU April/May

2001)16. What is the ratio of driving tension in flat belt, V belt and in rope dries?17. When the cross belt is used instead of open belt? 18. What is wipping? 19. Why lubrication reduces friction? (AU April/May 2007)20. What is the effect of centrifugal tension in belt? (AU Oct/Nov 2002)21. What do you mean by crowning in pulley?22. What is meant by initial tension in belt?23. List out the commonly used brakes?24. What is the minimum force required to slide a body on a rough horizontal

plane. (AU Nov /Dec 2004)25. What do you mean by a brake? (AU April/May 2007)26. Explain self energizing.

PART-B

1. A cone clutch is to transmit 7.5Kw at 900rpm. The cone has face angle of 12. The width of the face is half of the mean radius and normal pressure between the contact faces is not to exceed 0.09N/mm2. Assuming uniform wear and the co-efficient of friction between contact faces as 0.2. Find the main dimensions of the clutch and the axial forces required to engage the clutch. (AU May/June 2006)

2. Prove or disprove that “ Angle of friction is equal to angle of response”

3. Two pulleys one 450mm diameter and the other 200mm diameter are on parallel shafts 2.1m apart and are connected by a crossed belt. The larger pulley rotates at 225rpm. The maximum permissible tension in the belt is


1Kn and the coefficient of friction between the belt and the pulley is 0.25. Find the length of the belt required and the power that can be transmitted.

4. A bolt with a square threaded screw has mean diameter of 25mm and a pitch of 3mm. it carries an axial thrust of 10KN on the bolt head of 25mm mean radius. If coefficient of friction is 0.12. Find the force required at the end of a spanner 450mm long in tightening up the bolt.

5. Two tie rods are connected by a buckle having right and left handled threads. The threads are V-type and have a pitch of 5mm on a mean diameter of 30mm and a threaded angle of 60. Assuming co-efficient of friction as 0.15, find the torque required to produce a pull of 4*104N. (i) When the rods are tightened (ii) When the rods are loosened. (AU May/June 2006)

UNIT-IIIGEARING AND CAMS

PART-A

1. What is cam?2. Give some examples of cams.3. Define tangent cam.4. Differ radial and cylindrical cams. (AU April/May 2005) List any four types of

cam follower? (AU Nov /Dec 2004)5. What are the different motions of follower? 6. State the advantage of cam mechanism over link mechanism? (AU

April/May 2003)7. Define dwell period.8. Explain offset follower?9. Define pressure angle.

10. Define lift.11. Define undercutting in cam. (AU April/May 2005)12. How can you prevent undercutting in cam?13. What is bevel gearing? Mention its type.14. What is meant by Arc of approach, arc of recess and arc of contact?15. State law of gearing. (AU Oct/Nov 2002)16. Differentiate involute tooth profile and cycloidal tooth profile. (AU April/May

2005) 17. What are the methods to avoid interference?18. State the relationship between circular pitch and the module. (AU April/May

2003)19. What are the advantages and limitations of gear drive? Write any two.20. What is meant by contact ratio in gear? (AU April/May 2005)21. What do you know about tumbler gear?22. Define interference.23. Define circular pitch and diametral pitch in spur gears. 24. Explain any two methods of reducing or eliminating interference in gears.

(AU Oct/Nov 2002)25. Define backlash.


26. What is gear train? (AU April/May 2005)27. State any two advantages of involute gear. (AU Nov /Dec 2005)28. What are the types of gear trains?29. Write about reverted gear train with suitable sketch. (AU April/May 2003)30. Define simple gear train.31. What is meant by compound gear train32. What is the advantage of compound gear train over a simple gear train?33. What is reverted gear train?

PART-B

1. A disc cam is to give uniform motion to a knife edge follower during outstroke of 50mm during the first half of the cam revolution. The follower again returns to its original position with uniform motion during the next half of the revolution. The minimum radius of cam is 50mm and the diameter of the cam shaft is 35mm. draw the profile of the cam when, (i) the axis of the follower passes through the axis of the cam shaft, (ii) the axis of follower is offset by 20mm from the axis of the cam shaft. (AU April/May 2005)

2. Draw the profile of a cam operating with a knife edged follower having a light of 30mm. the cam raises the follower with SHM for 150 of its rotation followed by a period of dwell for 60. The follower descents for the next 100rotation of the cam uniform velocity, again followed by a dwell period. The cam rotates at a uniform velocity 120rpm and has a least radius of 20mm. what will be the maximum velocity and acceleration of the follower during the lift. (AU April/May 2005)

3. Design a cam for operating the exhaust valve of an oil engine. It is required to give equal uniform acceleration and retardation during opening and closing of the valve each of which corresponding to 60 of cam rotation. The valve must remains in the fully open position for 20 of cam rotation. The lift of the valve is 37.5mm and the least radius of the cam is 40mm. the follower is provided with a roller of radius 20mm and its line of stroke passes through the axis of the cam. (AU May/June 2006)

4. Draw the profile of the cam when the roller follower moves with an cycloidal motion a given below: (i) outstroke with maximum displacement of 44mm during 180 of cam rotation. (ii) Return stroke for the next 150 of cam rotation (iii) Dwell for the remaining 30 of cam rotation. The minimum radius of the cam is 20mm and the diameter of the roller is 10mm. the axis of the roller follower passes through the cam shaft axis.

5. Draw the profile of a cam operating a roller reciprocating follower and with the following data.(i) Minimum radius of cam=25mm, lift=30mm, roller diameter 15mm. the cam lifts the follower for 120 with SHM, followed by a dwell period of 30. Then the follower lower down during 150 of cam rotation with uniform acceleration and retardation followed by a dwell


period. If the cam rotates at a uniform speed of 150rpm. Calculate the maximum velocity and acceleration of the follower during the descent period. (AU May/June 2006)

6. A pair of involute spur gears with 16 pressure angle and module of 6mm is in mesh. The member of teeth on pinion is 16 and its rotational speed is 240 rpm. When the gear ratio is 1.75 in order to avoid interference, find (i) The addenda on pinion and gear wheel, (ii) The length of path of contact, (iii) The maximum velocity of sliding of teeth on either of the pitch point. (AU May/June 2006)

7. An epicyclic gear train consists of a sun wheel S, a stationary internal gear E and three identical planet wheels P carried on a star- shaped planet carrier. The size of different tooth wheels are such that the planet carrier C rotates at 1/5th of the speed of the sun wheel S. the minimum number of teeth on any wheel is 16. The driving torque on the sun wheel is 100Nm. Determine (i) Number of teeth on different wheels of the train, (ii) Torque necessary to keep the internal gear stationary. (AU April/May 2005)

8. Two gear wheels mesh externally to give a velocity ratio of 3 to 1. The involute tooth has 6mm module and 20 pressure angle. Addendum is equal to one module. The pinion rotates at 90rpm. Determine (i) number of teeth on pinion to avoid interference and the corresponding number on the wheel. (ii) The length of path and arc of contact (iii) contact ratio, 0iv) the maximum velocity sliding.

9. An epicyclic gear train consisting of fixed sun gear S with 50 teeth meshing with a planet gear, P with 40 teeth. The planet gear meshes with a ring gear, R with 60 teeth. Determine the speed of the ring gear when the arm, A which carries the planet gear rotates at a speed of 100rpm clockwise about the sun gear center axis.

10. A pair of 20 full depth involute spur gear having 30 and 50 teeth respectively of module 4mm are in mesh. The smaller gear rotates at 1000rpm. Determine (i) sliding velocity at engagement and at disengagement of pair of the teeth. (ii) Contact ratio.

11. Derive the Law of gearing. (AU May/June 2006)

UNIT-IVBALANCING

PART-A

1. Difference between static force analysis and dynamic force analysis.2. What do you mean by inertia?3. What is D’ Alembert’s principle?4. What do you mean by Equivalent offset inertia force?5. State the principle of superposition.6. Define piston effort and crank-pin effort.


7. Define inertia force.8. Write the importance of balancing?9. Write the different types of balancing?

10. Define static balancing.11. State the condition for static balancing.12. Write the condition for complete balancing?13. Define Dalby’s method of balancing masses.14. Why complete balancing is not possible in reciprocating engine?15. What are the various cases of balancing of revolving masses?16. Why the cranks of a locomotive are generally at right angle to one another?17. Define tractive force.18. What is swaying couple?19. What is the effect of hammer blow and what is the cause of it?20. What are in-line engines?21. What are the conditions to be satisfied for complete balance of in-line

engine?22. Why radial engines are preferred?

PART-B

1. a) A single cylinder reciprocating engine has a reciprocating mass of 60kg. The crank rotates at 60 rpm and the stroke is 320mm. Mass of revolving parts at 160mm radius is 40kg. If two-thirds of the reciprocating parts and the whole of the revolving parts are to be balanced, determine I) the balance mass required at a radius of 350mm ii) the unbalanced force when the crank has turned 50 degree from the IDC.(b) Explain partial balancing of unbalanced primary force in a reciprocating engine.

2. A shaft carries four masses A, B, C and D, which are radially attached to it. The mass centers are 3,3.8,4 and 3.5cm respectively from the axis of rotation. The masses A, C and D are 7.5kg, 5kg and 4 kg respectively. The axial distance between the plane of rotation of A and B is 40cm and between B and C is 50cm. The masses A and C are right angles to each other. Find for complete balance a) angle between the masses B and D from mass A b) axial distance between the planes of rotation of C and D and © magnitude of mass B.

3. A rotor has the following properties :

Mass Magnitude Radius Angle axial distance from mass A

A 9 kg 100 mm 0° ---- B 7 kg 120 mm 60° 160 mm C 8 kg 140 mm 135° 320 mm D 6 kg 120 mm 270° 560 mm


If the shaft is balanced by two counter masses located at 100-mm radii revolving in planes midway between planes A and B and midway between planes C and D. Determine the magnitudes of the masses and their respective angular position.

4. A shaft carries five masses w1; w2, w3, w4 and w5, which revolve at the same radius in planes which, are equidistant from one another. The magnitude of masses in planes 1,3,and 4 are 50kg, 40kg, 60 kg respectively. The position of masses 3 and 4 with respect to mass 1 are 60 and 120 degrees respectively. Determine the weights in planes 2 and 5 and their positions with respect to plane 1, in order to put the shaft in complete rotating balance.

5. An engine has two cylinders in the form of V, the centerlines of the cylinders being in one plane and inclined at 45 degrees on either side of a central vertical. The two connecting rods works on the same crank. The weight of the reciprocating pars for each cylinder is 0.5 kg. The crank radius is 4.5 cm and the length of the connecting rod is 18 cm. Show that the vertical force on this engine due to secondary force is zero, and that if suitable balance weights are attached to the crank shaft, the primary inertial forces can be reduced to zero.

6. The revolving masses for a single crank engine are equivalent to a mass of 80kg at a radius of 250mm. Determine the position and magnitude of the balance mass at a radius of 300mm in two planes L and R at a distance of 150mm and 400mm from the plane of the crank, if (a) these planes L and R are on the same side of the crank and (b) these planes are on the opposite sides of the crank.

7. The piston of a 60 degree twin V-engine has strokes of 120mm. The connecting rods driving a common crank have a length of 200mm. The mass of reciprocating parts per cylinder is 1.2kg and the speed of crankshaft is 2000rpm. Determine the magnitude of primary and secondary forces.

8. A four cylinder engine has the two outer cranks at 120 degree to each other and their reciprocating masses are each 400kg. The distance between the planes of rotation of adjacent cranks is 400,700 and 500mm. Find the reciprocating mass and the relative angular position for each of the inner cranks, if the engine is to be in complete primary balance. Also find the maximum unbalanced secondary force, if the length of each crank is 350mm, the length of each connecting rod is 1.7m and the engine speed is 500rpm.

9. A V type twin engine has cylinder axis at right angles and the connecting rods operate a common crank. The reciprocating mass per cylinder is 12kg. The crank is 70mm connecting rods are 350mm. Show that the


engine may be balanced for primary effects by means of a revolving balance weight.

10. Three cylinders of an air compressor have their axes at 120 degrees to one another and their connecting rods are coupled to a simple crank. The stroke is 10cm and the length of each connecting rod is 15cm. Mass of the reciprocating parts per cylinder is 1.5kg. Determine the primary and secondary forces of the engine running at 1000rpm.

UNIT-VVIBRATION

PART-A

1. What are the causes of vibration?2. Define Period and cycle of vibration.3. Define frequency of vibration.4. How will you classify vibration?5. What is meant by free vibration and forced vibrations?6. What do you meant by damping and damped vibration?7. Define resonance.8. What do you mean by a degree of freedom ?9. A cantilever beam has infinite number of degrees of freedom.

10. Define steady state and transient vibrations.11. What is equivalent spring stiffness?12. List out the various methods of finding the natural frequency of free

longitudinal vibrations.13. What is the principle of Rayleigh’s method of finding natural frequency of

vibrations?14. A shaft supported in long bearing is assumed to have both ends fixed for

solving transverse vibration problems.15. The damping force per unit velocity is known as damping coefficient.16. Distinguish between critical damping and large damping.17. When do you say a vibrating system is under damped?18. Define critical or whirling or whipping speed of a shaft.19. What are the factors that affect the critical speed of a shaft?20. What are the causes of critical speed?21. Define damping ratio.22. Define logarithmic decrement.23. What is meant by dynamic magnifier or magnification factor?24. What is meant by transmissibility?25. Define transmissibility ratio or isolation factor.26. Briefly explain elastic suspension.27. Specify any two industrial application where the transmissibility effects of

vibration are important. 28. Specify the importance of vibration isolation?29. What are the methods of isolating the vibration?30. Define torsional vibration.31. Differentiate between transverse and torsional vibration.


32. Define node in torsional vibration.33. Define torsional equivalent shaft.34. What are the conditions to be satisfied for an equivalent system to that of

geared system in torsional vibrations?

PART-B

1. Derive an expression for the natural frequency of the free longitudinal vibrations by (i) Equilibrium method. (ii) Energy method. (AUQ-A/M 2003)

2. A lorry of mass 3.64 tonnes when empty is observed to settle 46 mm during the loading of 3 tonnes of cargo of cargo. What period of vertical vibration will the lorry have on its spring: (a) when loaded: and (b) when empty?

3. A steel wire (E = 1.96 x 1011 N/m2) is of 2 mm diameter and is 30 metres long. It is fixed at the upper end and carries a mass ‘m’ kg at ita lower end. Find ‘m’ so that the frequency of longitudinal vibrations is 4 cycles / sec.

4. Determine the equivalent spring sriffness and the natural frequency of the vibrating systems shown in Fig.7.12(a) to (e), when

(a) The mass is suspended to a spring,(b) The mass is suspended at the bottom of two springs inseries,(c) The mass is fixed in between two springs,(d) The mass is fixed to the mid-point of a spring, and the mass is supended

at the bottom of two springs in parallel.

5. Find the equivalent stiffness of vibration of the system shown in Fig. If s1 =

5000 N/m, s2 = s3 = 8000 N/m and m = 25 kg, find the natural frequency of vibration of the system.

6. A vibrating system consists of a mass of 8 kg, spring of stiffness 5.6 N/m and a dashpot of damping coefficient of 40 N/m/s. Find :

(a) the critical damping coeeficient,(b) the damping factor,(c) the natural frequency of damped vibration,(d) the logarithmic decrement,(e) the ratio of two consecutive amplitudes, and (f) the number of cycles after which the original amplitude is reduced to

20 percent.

7. In a single degree of damped vibrating system, a suspended mass of 3.75 kg makes 12 oscillations in 7 seconds when disturbed from its equilibrium position. The amplitude of vibration reduces to 0.33 of its


initial value in four oscillations. (i) Stiffness of the spring, (ii) logarithmic decrement, (iii) damping factor and (iv) damping coefficient. (AUQ- N/D 2003)

8. The barrel of a large gun recoils against a spring on firing. At the end of the firing, a dash pot is engaged that allows the barrel to return to its original position in minimum time without oscillation. Gun barrel mass is 400 kg and initial velocity of recoil is 20m/s. The barrel recoils 1m. Determine spring stiffness and critical damping coefficient of dash pot. (AUQ-N/D 2003)

9. A vertical shaft 25 mm diameter and 0.75 m long is mounted in long bearings and carries a pulley of mass 10 kg midway between the bearings. The centre of pulley is 0.5 mm from the axis of the shaft. Find (a) the whirling speed and (b) the bending stress in the shaft, when it is rotating at 1700 r.p.m. Neglect the mass of the shaft and take E = 200 GN/m2

10. A shaft of 180 mm diameter is supported by two bearings 2.5 meters apart. It carries three discs of mass 250 kg, 500 kg and 200 kg at 0.6 m, 1.5 m and 2 m from the left hand. Assuming mass of the shaft as 190 kg/m, determine critical speed of the shaft. Take E = 211 GN/m2.

11. A shaft of 75 mm diameter and 2 m long is fixed at both the ends vertically, as shown in Fig. A flywheel of mass one tonne is provided on the shaft at a distance of 1.5 m from its upper end as shown. The flywheel’s radious of gyration is 800 mm. Find the natural frequency of vibration of the system. Take C = 8 10 N/mm2.

12. The flywheel of an engine driving a dynamo has a mass of 180 kg and a radius of gyration of 30 mm. The shaft at the flywheel end has en effective length of 250 mm and is 50 mm diameter. The armature mass is 120 kg and its radius of gyration is 22.5 mm. The dynamo shaft is 443 mm diameter and200 mm effective length. Calculate the position of node and frequency of torsional oscillation. Take C = 83 kN/mm2.

13. The two rotors A and B are attached to the end of a shaft 500 mm long. The mass of the rotor A is 300 kg and its radius of gyration is 300 mm. the corresponding values of the rotor B are 500 kg and 450 mm respectively. The shaft is 70 mm in diameter for the first 250 mm; 120 mm for the next 70 mm and 100 mm diameter for the remaining length. The modulus of rigidity for the shaft material is 80 GN/m2. Find: 1. The position of the node, and 2. The frequency of tosional vibration.

14. The two equal masses of 500 kg and radius of gyration 37.5 cm are keyed to opposite ends of a shaft is 7.5 cm dia. For the first 25 cm and 12.5 cm dia. for the next 10 cm and 8.75 cm. for theremainder of its length. Find


the natural frequency of the free torsional vibration of the system and the position of the node. Take G = 8 x 106 N/cm2

15. An instrument vibrate with a frequency of 1 Hz when ther is no damping. When damping is provided, the frequency was observed to br 0.9 Hz. Find the (i) damping factor, and (ii) logarithmic decrement. Given data : fn = fd = 0.9 Hz

16. A mass of 50 kg suspended from a spring produces a statical deflection of 17 mm and when in motion it experiences viscous damping force of value 250 N at a velocity of 0.3 m/s. Calculate the periodic time of damped vibration. If the mass is then subjected to a periodic disturbing force having a maximum value of 260 N and making 2 cycles, find the amplitude of ultimate motion.

17. A mass of 50 kg is supported by an elastic structure of total stiffness 20 KN/m. The damping ration of the system is 0.2. A simple harmonic disturbing force acts on the mass and at any time t seconds, the force is 60 sin 10t newtons. Find the amplitude of the vibrations and the phase angle caused by the damping

18. A spring mass system is excited by a force F sin wt. On measuring, the amplitude of vibration is found to be 12 mm at resonance. However, at a frequency 0.8 times the resonant frequency, the amplitude reduces to 8 mm. Determine the damping ratio of the system.

19. A refrigerator unit having a mass of 40 kg is to be supported on four springs, each having a spring stiffness ‘s’. The unit operators at 500 r.p.m. Find the value of stiffness ‘s’ if only 20% of the shaking force is allowed to be transmitted to the supporting structure.

20. A compressor supported symmetrically on four springs has a mass of 100 kg. The mass of the reciprocating parts is 2 kg which move through a vertical stroke of 80 mm with SHM. Neglecting damping, determine the combined stiffness of the springs so that the force transmitted to the foundation is 1/25th of the impressed force. The machine crankshaft rotates at 1000 r.p.m. When the compressor is actually supported on the springs, it is found that the damping reduces the amplitude of successive free vibrations by 25%. Find(i) the force transmitted to the foundation at 1000 r.p.m.,(ii) the force transmitted to the foundation at resonance, and (iii) the amplitude of the vibrations at resonance.


21. Find the stiffness of each spring when a refrigerator unit having a mass of 30 kg is to be supported by three springs. The force transmitted to the supporting structure is only 10% of the impressed force. The refrigerator unit operates at 420 r.p.m.

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Question Bank - Mechanics of Machines.doc