Which of the following affects the elasticity of a substance

1. Hammering and annealing

2. Change in temperature

3. Impurity in substance

4. All of these

Which one of the following quantities does not have the unit of force per unit area?

1. Stress                                      

2. Strain

3. Young's modulus of elasticity

4. Pressure

The length of an elastic string is a metre when the longitudinal tension is 4 N and b metre when the longitudinal tension is 5 N. The length of the string in metre when the longitudinal tension is 9 N is

1. a - b                                             

2. 5b - 4a

3. 2b -$\frac{1}{4}\mathrm{a}$                                       

4. 4a - 3b

The force required to stretch a steel wire of cross-section $1<mspace\; width="1em"></mspace>{\mathrm{cm}}^2$ to 1.1 times its length would be $\left(Y=2\times {10}^{11}<mspace\; width="1em"></mspace>N{m}^{-2}\right)$

1. $2\times {10}^{6}N$                               

2. $2\times {10}^{3}N$

3. $2\times {10}^{-6}N$                             

4. $2\times {10}^{-7}N$

A wire of diameter 1mm  breaks under a tension of 1000 N. Another wire, of the same material as that of the first one, but of diameter 2 mm, breaks under a tension of:

1. 500 N                               

2. 1000 N

3. 10000 N                           

4. 4000 N

The possible value of Poisson's ratio is

1. 1                                       

2. 0.9

3. 0.8                                     

4. 0.4

There is no change in the volume of a wire due to change in its length on stretching. The Poisson's ratio of the material of the wire is

1. + 0.50                               

2.  – 0.50

3.  0.25                                  

4.  – 0.25

A copper wire and a steel wire of the same diameter and length are connected end to end and a force is applied, which stretches their combined length by 1 cm. The two wires will have

1. Different stresses and strains

2. The same stress and strain

3. The same strain but different stresses

4. The same stress but different strains

A fixed volume of iron is drawn into a wire of length L. The extension x produced in this wire by a constant force F is proportional to:

1. $\frac{1}{L^2}$                                             

2. $\frac{1}{L}$

3. $L^2$                                               

4. L