Two rods of different materials having coefficients of linear expansion α1 and α2 , Young's modulii Y1 and Y2 respectively are fixed between two rigid massive walls. The rods are heated such that they undergo the same increase in temperature. There is no bending of rods. If α1 : α2 =2 : 3, the thermal stresses developed in the two rods are equal provided Y1 : Y2 is equal to :
2 : 3
1 : 1
3 : 2
4 : 9
A uniform elastic plank moves due to a constant force F placed over a smooth surface. The area of end face is S and Young's modulus of the material is E. What is the average strain produced in the direction of the force?
F/4SE
Zero
F/SE
F/2SE
The Young's modulus of a wire is Y. If the energy per unit volume is E, then the strain will be :
EY
E/Y
The magnitude of the force developed by raising the temperature from 0oC to 100oC of the iron bar 1.00 m long and 1 cm2 cross-section when it is held so that it is not permitted to expand or bend is :
(Given : α = 10-5 /oC and Y = 1011 N/m2)
103 N
104 N
105 N
109 N
A steel wire of uniform cross-section of 2 mm2 is heated upto 50oC and clamped rigidly at two ends. If the temperature of wire falls to 30oC then change in tension in the wire will be :
(Given : Coefficient of linear expansion of steel is 1.1 x 10-5°C and Young's modulus of elasticity of steel is 2 x 1011N/m2)
22 N
44 N
88 N
132 N
The upper end of a wire, 1 m long and 4 mm radius, is clamped. The lower end is twisted by an angle of 30o. The angle of shear at the surface is :
12o
1.2o
0.12o
0.012o
The length of an iron wire is L and area of cross-section is A. The increase in length is l on applying the force F on its two ends. Which of the statement is correct ?
Increase in length is inversely proportional to A
Increase in length is proportional to Young's modulus
Increase in length is inversely proportional to its length L
Increase in length is proportional to area of cross-section A
A bridge can bear 4 x 104 kg weight. If the breaking stress is 47 x 103 N/m3 and factor of safety is 5 then the area of cross section of the rod will be :
4.34 m2
43.4 m2
0.434 m2
0.04 m2
A metal block is experencing an atmospheric pressure of 105 N/m2. When the same block is placed in a vaccum chamber, the fractional change in its volume : (the bulk modulus of metal is 1.25 x 1011 N/m2)
8 x 10-7
1 x 10-7
4 x 10-7
2 x 10-7