### Strength of Materials (Stresses and Strains)

Q.1.      A bar of diameter 30 mm is subjected to a tensile load such that the measured extension on a gauge length of 200 mm is 0.09 mm and the change in diameter is 0.0045 mm. The Poisson’s ratio will be
(a)  1/4
(b)  1/3
(c)  1/4.5
(d)  1/2                            (IES 1995)

Q.2.     A steel cube of volume 8000 cc is subjected to all round stress of 1330 kg/sq.cm. The volumetric change is

(a)  8 cc
(b)  6 cc
(c)  0.8 cc
(d)  0.01 cc                     (IES 1995)

Q.3.      A steel tube is surrounding a solid aluminium cylinder. A force P is applied at the assembly. The aluminium cylinder is 75 mm in diameter and outside diameter of the steel tube is 90 mm. Given Esteel = 200 GNm-2 and Ealuminium =25 GNm-2 If P = 200 kN, the stress in steel tube will be
(a)  10 MPa
(b)  60.75 MPa
(c)  80.25 MPa
(d)  100 MPa

Q.4.      In the above problem, stress in aluminium will be
(a)  10 Mpa
(b)  60.75 MPa
(c)  80.25 MPa
(d)  100 MPa

Q.5.      A bar of length L is fitted between two supports and the temperature is increased t0. If support does not yield, the temperature stress in the bar will be
(a)  0
(b)  tE
(c)  at
(d)  atE

Q.6.      The length, coefficient of thermal expansion and Young’s modulus of bar A are twice that of bar B. If the temperature of both bars is increased by the same amount while preventing any expansion, then the ratio of stress developed in bar A to that in bar B will be
(a)  2
(b)  4
(c)  8
(d)  16                             (IES 1996)

Q.7.      A steel bar, 300 mm long and 24 mm diameter, is turned down to 18 mm diameter for one third of its length. It is heated 300C above room temperature, clamped at both ends and then allowed to cool to room temperature. If the distance between the clamped is unchanged, the maximum stress in the bar(a = 12.5 x 10-6 per 0C and E = 200 GN/m2) is
(a)  25 MN/m2
(b)  50 MN/m2
(c)  75 MN/m2
(d)  100 MN/m2            (IES 2000)

Q.8.      A railway track is laid so that there is no stress in the rails at 100C. If there is no allowance for expansion then stress in the rails at 600 C will be
(a)  53.3 N/mm2
(b)  110.7 N/mm2
(c)  115 N/mm2
(d)  120 N/mm2

Q.9.      In the above problem if there is an expansion allowance of 10 mm per rail then stress in the rails at 600 will be
(a)  53.3 N/mm2
(b)  110.7 N/mm2
(c)  115 N/mm2
(d)  120 N/mm2

Q.10.      In the above problem what will be expansion allowance if stress induced is zero
(a)  1 mm
(b)  7 mm
(c)  11 mm
(d)  18 mm

1. b
2. a
3. c
4. a
5. d
6. b
7. d
8. d
9. a
10. d