Machine Design

31. Fibrous fracture occurs in

1. ductile material
2. brittle material
3. elastic material
4. hard material
5. all of the above.

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32. For applications involving high stresses in one direction only the following type of thread would be best suited

1. ISO metric thread
2. acme thread
3. square thread
4. buttress thread
5. British Association thread.

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33. For standard coarse threads of nut, the threads will be as strong in failure by shear as the bolt in tension, if the height of nut (h) is approximately

1. 0.4 times
2. 0.6 times
3. 0.7 times
4. 0.8 times
5. 0.9 times the normal diameter of bolt.

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34. For steel, the ultimate strength in shear as compared to ultimate strength in tension is

1. same
2. 43862
3. 43891
4. 43922
5. 43892

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35. For tight leakage joints, following type of thread is best suited

1. metric
2. buttress
3. square
4. acme
5. NPT (national pipe threads).

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36. Form coefficient of spring is

1. ratio of coil diameter to wire diameter
2. load required to produce unit deflection
3. its capability of storing energy
4. concerned With strength of wire of spring
5. nothing

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37. Gear box is used

1. to produce torque
2. for speed reduction
3. to obtain variable speeds
4. to increase efficiency of system
5. to damp out vibrations.

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38. Guest's theory of failure is applicable for following type of materials

1. brittle
2. ductile
3. elastic
4. plastic
5. tough.

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39. I.S. specifies following total number of grades of tolerances

1. 18
2. 16
3. 20
4. 22
5. 14

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40. If a load W is applied instantaneously on a bar; then the stress induced in bar will

1. be independent of ratio of mass of load W to mass of bar (y)
2. increase with increase in y
3. decrease with decrease in y
4. depend on other considerations
5. none of the above.

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