Choose the correct statement.
1. | Breaking stress does not depend on the area of cross-section. |
2. | \(\mathrm{B}_{\text {solid }}>\mathrm{B}_{\text {gas }}>\mathrm{B}_{\text {liquid }}\)where B is the bulk modulus. |
3. | Breaking load does not depend on the area of cross-section. |
4. | Young's modulus always decreases on decreasing the temperature. |
A steel ring of radius \(\mathrm{r}\) and cross-section area \(\mathrm{A}\) is fitted onto a wooden disc of radius \(\mathrm{R}(\mathrm{R}>\mathrm{r}).\) If Young's modulus is \(\mathrm{E},\) then the force with which the steel ring is expanded is:
1. | \(\mathrm{AE} \frac{\mathrm{R}}{\mathrm{r}} \) | 2. | \(A E \frac{R-r}{r} \) |
3. | \(\frac{E}{A} \frac{R-r}{A} \) | 4. | \(\frac{\mathrm{Er}}{\mathrm{AR}}\) |
A light rod of length 2m is suspended from the ceiling horizontally by means of two vertical wires of equal length. A weight W is hung from the light rod as shown in the figure. The rod is hung by means of a steel wire of cross-sectional area and brass wire of cross-sectional area . To have equal stress in both wires, =?
1. | 1/3 | 2. | 1/4 |
3. | 4/3 | 4. | 1/2 |
The stress versus strain graphs for wires of two materials A and B are as shown in the figure. If are the Young's moduli of the materials, then:
1. | YB = 2YA | 2. | YA = YB |
3. | YB = 3YA | 4. | YA = 3YB |
A vessel of \(1\times 10^{-3}\) m3 volume contains oil. When a pressure of \(1.2 \times10^5\) N/m2 is applied on it, then volume decreases by \(0.3 \times 10^{-6}\) m3. The bulk modulus of oil is:
1. | \(1 \times 10^6 \mathrm{~N} / \mathrm{m}^2 \) | 2. | \(2 \times 10^7 \mathrm{~N} / \mathrm{m}^2 \) |
3. | \(4 \times 10^8 \mathrm{~N} / \mathrm{m}^2 \) | 4. | \(6 \times 10^{10} \mathrm{~N} / \mathrm{m}^2\) |
The stress-strain curves are drawn for two different materials \(X\) and \(Y.\) It is observed that the ultimate strength point and the fracture point are close to each other for material \(X\) but are far apart for material \(Y.\) We can say that the materials \(X\) and \(Y\) are likely to be (respectively):
1. | ductile and brittle |
2. | brittle and ductile |
3. | brittle and plastic |
4. | plastic and ductile |
A wire can sustain a weight of 10 kg before breaking. If the wire is cut into two equal parts, then each part can sustain a weight of:
1. | 2.5 kg | 2. | 5 kg |
3. | 10 kg | 4. | 15 kg |
A 1000 kg lift is tied with metallic wires of maximum safe stress of 1.4 108 N m-2. If the maximum acceleration of the lift is 1.2 m s-2, then the minimum diameter of the wire is:
1. 1 m
2. 0.1 m
3. 0.01 m
4. 0.001 m
A wire of negligible mass and length 2 m is stretched by hanging a 20 kg load to its lower end keeping its upper end fixed. If work done in stretching the wire is 50 J, then the strain produced in the wire will be:
1. 0.5
2. 0.1
3. 0.4
4. 0.25
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 will be:
1. | \(a-b\) | 2. | \(5b-4a\) |
3. | \(2b-\frac{1}{4}a\) | 4. | \(4a-3b\) |