SECTION-5

#### Strength of Material MCQ

##### Q41. Choose the wrong statement

(a) Elongation produced in a rod (by its own weight) which is rigidly fixed at the upper end and hanging is equal to that produced by a load half its weight applied at the end.
(b) The stress at any section of a rod on account of its own weight is directly proportional to the distance of the section from the lower end.
(c) Modulus of elasticity is having the same unit as stress.
(d) If a material expands freely due to heating, it will develop thermal stresses.

Ans:(d) If a material expands freely due to heating, it will develop thermal stresses.

##### Q42. A rod of length (l) tapers uniformly from a diameter D1 to a diameter D2 and carries an axial tensile load P. The extension of the rod would be

$\text { (a) } \frac{\pi P l}{4 E D_{1} D_{2}}$

$\text { (b) } \frac{4 P l}{\pi E D_{1} D_{2}}$

$\text { (c) } \frac{\pi E P l}{4 D_{1} D_{2}}$

$\text { (d) } \frac{4 P E l}{\pi D_{1} D_{2}} .$

Ans:$\text { (b) } \frac{4 P l}{\pi E D_{1} D_{2}}$

##### Q43. A rod of length (l) tapers uniformly from a diameter D1 to a diameter D2 and carries an axial tensile load P, the rod is of uniform diameter (D), then extension would be

$\text { (a) } \frac{\pi P l}{4 E D^{2}}$

$\text { (b) } \frac{4 P l}{\pi E D^{2}}$

$\text { (c) } \frac{\pi E P l}{4 D^{2}}$

$\text { (d) } \frac{4 P E l}{\pi D^{2}}=$

Ans:$\text { (b) } \frac{4 P l}{\pi E D^{2}}$

##### Q44. A rod of length l and cross-sectional area A rotates about an axis passing through one end of the rod. The extension produced in the bar due to centrifugal forces would be

$\text { (a) } \frac{w \omega l^{2}}{3 E}$

$\text { (b) } \frac{w \omega^{2} l^{3}}{g E}$

$\text { (c) } \frac{w \omega^{2} l^{3}}{3 g E}$

$\text { (d) } \frac{3 g E}{w \omega^{2} p^{3}} .$

Ans:$\text { (b) } \frac{w \omega^{2} l^{3}}{g E}$

##### Q45. If D is the diameter of a sphere, then volumetric strain is equal to

(a) two times the strain of diameter
(b) 1.5 times the strain of diameter
(c) three times the strain of diameter
(d) the strain of diameter.

Ans:(c) three times the strain of diameter

##### Q46. If l be the length and D be the diameter of a cylindrical rod, then volumetric strain of the rod is equal to

(a) strain of length plus strain of diameter
(b) strain of diameter
(c) strain of length + twice the strain of diameter
(d) strain of length.

Ans:(c) strain of length + twice the strain of diameter

(a) same
(b) double
(c) three times
(d) half.

Ans:(b) double

(a) half
(b) same
(c) double
(d) three times.

Ans:(c) double

##### Q49. The instantaneous stress (f) induced in a bar of length (l) and of cross-sectional area (A) due to impact load P, falling from a height h, is equal to

$\text { (a) } \frac{P}{A}+\sqrt{\frac{P^{2}}{A^{2}}+\frac{2 P h E}{A l}}$

$\text { (b) } \frac{P}{A}+\sqrt{\frac{P^{2}}{A^{2}}-\frac{2 P h E}{A l}}$

$\text { (c) } \frac{P}{A}+\sqrt{1+\frac{2 P h E}{A l}}$

$(d) \frac{P}{A}+\sqrt{1+\frac{2 h A E}{P l}}$

Ans:$\text { (a) } \frac{P}{A}+\sqrt{\frac{P^{2}}{A^{2}}+\frac{2 P h E}{A l}}$

##### Q50. For the bars of composite section

(a) the load carried by different materials is the same as the total external load
(b) the extension in different materials is different
(c) the total external load is equal to the total sum of the loads carried by different materials
(d) strain in all materials is equal
(e) both (c) and (d).

Ans:(c) the total external load is equal to the total sum of the loads carried by different materials

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##### Read More Sections of Strength of Material

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Strength of Material MCQ – Section-1

Strength of Material MCQ – Section-2

Strength of Material MCQ – Section-3

Strength of Material MCQ – Section-4

Strength of Material MCQ – Section-5

Strength of Material MCQ – Section-6