Strength of Materials

21. If the radius of wire stretched by a load is doubled, then its Young's modulus will be

1. doubled
2. halved
3. become four times
4. become one-fourth
5. remain unaffected.

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22. If the rivets in adjacent rows are staggered and the outermost row has only one rivet, the arrangement of the rivets is called

1. chain riveting
2. zig zag riveting
3. diamond riveting
4. criss-cross riveting
5. none of the above.

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23. In a belt drive, the pulley diameter is doubled, the belt tension and pulley width remaining same. The changes required in key will be

1. increase key length
2. increase key depth
3. increase key width
4. double all the dimensions
5. none of the above.

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24. In a prismatic member made of two materials so joined that they deform equally under axial stress, the unit stresses in two materials are

1. equal
2. proportional to their respective moduli of elasticity
3. inversely proportional to their moduli of elasticity
4. average of the sum of moduli of elas-ticity
5. none of the above.

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25. In a tensile test on mild steel specimen, the breaking stress as compared to ultimate tensile stress is

1. more
2. less
3. same
4. more/less depending on composition
5. may have any value.

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26. In a tensile test, near the elastic limit zone, the

1. tensile strain increases more quickly
2. tensile strain decreases more quickly
3. tensile strain increases in proportion to the stress
4. tensile strain decreases in proportion to the stress
5. tensile strain remains constant.

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27. In question 56, the internal reaction in bottom 80 cm length will be

1. same in both cases
2. zero in first case
3. different in both cases
4. data are not sufficient to determine same
5. none of the above.

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28. In riveted boiler joints, all stresses, shearing, bearing and tensile are based on the

1. size of rivet
2. size of the drilled or reamed hole
3. average of size of rivet and hole
4. smaller of the two
5. any one of the above.

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29. In the tensile test, the phenomenon of slow extension of the material, i. e. stress increasing with the time at a constant load is called

1. creeping
2. yielding
3. breaking
4. plasticity
5. none of the above.

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30. It equal and opposite forces applied to a body tend to elongate it, the stress so produced is called

1. internal resistanpe
2. tensile stress
3. transverse stress
4. compressive stress
5. working stress.

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