The metal rod (Y = 2 x ${10}^{12}$ dyne/sq. cm) of the coefficient of linear expansion 1.6 x ${10}^{-5}$ per °C has its temperature raised by 20°C. The linear compressive stress to prevent the expansion of the rod is:

(1) 2.4 x ${10}^8$ dyne/sq. cm

(2) 3.2 x ${10}^8$ dyne/sq. cm

(3) 6.4 x ${10}^8$ dyne/sq. cm

(4) 1.6 x ${10}^8$ dyne/sq. cm

One end of a uniform wire of length L and weight ${\mathrm{W}}_0$, is attached rigidly to a point in the roof and weight ${\mathrm{W}}_1$ is suspended from its lower end. If S is the area of cross-section of the wire, the stress in the wire at a height L/4 from its lower end is:

(1) ${\mathrm{W}}_1$/S

(2) [${\mathrm{W}}_1$ + (${\mathrm{W}}_0$/4)]/S

(3) [${\mathrm{W}}_1$ + (3${\mathrm{W}}_0$/4)/S

(4) (${\mathrm{W}}_1$ + ${\mathrm{W}}_0$)/S

An elongation of 0.1% in a wire of cross-sectional area ${10}^{-6} {\mathrm{m}}^2$ causes tension of 100 N. The Young's modulus is:

(1) ${10}^{12}$ $\mathrm{N}/{\mathrm{m}}^2$

(2) ${10}^{11}$ $\mathrm{N}/{\mathrm{m}}^2$

(3) ${10}^{10}$ $\mathrm{N}/{\mathrm{m}}^2$

(4) ${10}^2$ $\mathrm{N}/{\mathrm{m}}^2$

The elongation (\(X\)) of a steel wire varies with the elongating force (\(F\)) according to the graph:
(within elastic limit)

1.		2.
3.		4.

A steel ring of radius r and cross-section area A is fitted on to a wooden disc of radius R (R > r). If Y is Young's modulus of elasticity, then tension with which the steel ring is expanded is:

1.  $\frac{\mathrm{AYR}}{\mathrm{r}}$

2.  $\frac{\mathrm{AY}\left(\mathrm{R} - \mathrm{r}\right)}{\mathrm{r}}$

3.  $\frac{\mathrm{Y}\left(\mathrm{R} - \mathrm{r}\right)}{\mathrm{Ar}}$

4.  $\frac{\mathrm{Yr}}{\mathrm{AR}}$

Young's modulus of a material is 2.4 times that of its modulus of rigidity. Its Poisson's ratio is:

(1) 1. 2

(2) 2. 4

(3) 0. 2

(4) 0. 4

The longitudinal strain of a string is equal to twice the magnitude of lateral strain. Poisson's ratio of the material of string is:

(1) 0.4

(2) 0.5

(3) 0.1

(4) 0.2

When a mass M is suspended by a wire, it elongates the wire by length l. The work done during this elongation process is:

(1) Zero

(2) $\frac{1}{2}$Mgl

(3) Mgl

(4) 2Mgl

Given that the breaking stress of a wire is 7.2 x ${10}^7$ N/ ${\mathrm{m}}^2$ and its density is 7.2 g/cc, then the maximum length of the wire which can hang without breaking is: (g = 10 m/${\mathrm{s}}^2$)

(1) 1000 m

(2) 100 m

(3) 200 m

(4) 50 m

Work done in increasing the length of a \(1~\text m\) long wire by \(1 ~\text{mm}\) is \(10 ~\text J.\) The work done in increasing the length further by \(1 ~\text{mm}\) is:
1. \(10 ~\text J\)
2. \(20 ~\text J\)
3. \(30 ~\text J\)
4. \(40 ~\text J\)