148. For a given material Young's modulus is 200 GN/m2 and modulus of rigidity is 80 GN/m2. The value of Poisson's ratio is

A.0.15

B.0.2

C.0.25

D. 0.40.

149. The ratio of strengths of solid to hollow shafts, both having outside diameter D and hollow having inside diameter D/2, in torsion, is

A. 1/4

B. ?

C. 1/16

D. 15/16

150. During a tensile test on a ductile material

A. nominal stress at fracture is higher than the ultimate stress

B. true stress at fracture is higher than the ultimate stress

C. true stress at fracture is the same as the ultimate stress

D. none of these.

151. A rectangular log of wood is floating in water with a load of 100 N at its centre. The maximum shear force in the wooden log is

A. 50 N at each end

B. 50 N at the centre

C. 100 N at the centre

D. none of these,

152. A cast iron T section beam is subjected to pure bending. For maximum compressive stress to be three times the maximum tensile stress, centre of gravity of the section from flange side is

A. h/4

B. h/3

C. h/2

D. 2/3 h.

153. While testing a cast iron beam (2.5 cm x 2.5 cm) in section and a metre long simply supported at the ends failed when a 100 kg weight is applied at the centre. The maximum stress induced is :

A. 960 kg/cm2

B. 980 kg/cm2

C. 1000 kg/cm2

D. 1200 kg/cm2.

154. The cross sections of the beams of equal length are a circle and a square whose per- missible bending stress are same under same maximum bending. The ratio of their flexural weights is,

A.1.118

B.1.338

C.1.228

D. 1.108.

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