Machine Design

41. If a material fails below its yield point, failure would be due to

1. straining
2. fatigue
3. creep
4. sudden loading
5. impact loading.

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42. If a spring is cut down into two springs, the stiffness of cut springs will be

1. half
2. same
3. double
4. unpredictable
5. none of the above.

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43. If an application calls for stresses on screw threads in one direction only, then the following type of thread would be best suited

1. square
2. acme
3. buttress
4. BSW
5. metric.

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44. If an unsupported uniform cross sectional elastic bar is subjected to a longitudinal impact from a rigid bob moving with velocity v, then a compressive wave of intensity sc is propagated through the bar as follows

1. vpE
2. vVvF
3. WpE/2
4. IvHpE
5. none of the above, where E = modulus of elasticity and p = mass density.

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45. If d is the diameter of bolt hole then for a flanged pipe joint to be leak proof, the circumferential pitch of the bolts should be

1. lOVZ
2. 10VZtol5Vd
3. 15Vdto20VZ
4. 20Vdto30Vd
5. 30V5"to40Vd.

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46. If d is the normal diameter of a bolt in mm, then the initial tension in kg in a bolt used for making a fluid tight joint as for steam engine cover joint is calculated by the relation

1. 102 d
2. 124 d
3. 138 d
4. 151 d
5. 168 d.

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47. If p = bearing pressure on projected bearing area, z = absolute viscosity of lubricant, and N = speed of journal, then the bearing characteristic number is given by

1. ZN/p
2. p/ZN
3. Z/pN
4. N/Zp
5. Zp/N.

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48. If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to

1. diameter of bolt
2. 0.75 x diameter of bolt
3. 1.25 x diameter of bolt
4. 1.5 x diameter of bolt
5. 0.5 x diameter of bolt.

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49. If the tearing efficiency of a riveted joint is 75%, then the ratio of diameter of rivet to the pitch is equal to

1. 0.2
2. 0.25
3. 0.5
4. 0.6
5. 0.75.

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50. If threads on a bolt are left hand, threads on nut will be

1. right hand with same pitch
2. left hand with same pitch
3. could be left or right hand
4. right hand with fine pitch
5. left hand with fine pitch.

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