Three wires \(A,\) \(B,\) \(C\) made of the same material and radius have different lengths. The graphs in the figure show the elongation-load variation. The longest wire is:
1. \(A\)
2. \(B\)
3. \(C\)
4. All of the above
The bulk modulus of a spherical object is \(B\). If it is subjected to uniform pressure \(P\), the fractional decrease in radius will be:
1. \(\frac{P}{B}\)
2. \(\frac{B}{3P}\)
3. \(\frac{3P}{B}\)
4. \(\frac{P}{3B}\)
1. | \(1:2\) | 2. | \(2:1\) |
3. | \(4:1\) | 4. | \(1:1\) |
The area of cross-section of a wire of length \(1.1\) m is \(1\) mm2. It is loaded with mass of \(1\) kg. If Young's modulus of copper is \(1.1\times10^{11}\) N/m2, then the increase in length will be: (If \(g = 10~\text{m/s}^2)\)
1. | \(0.01\) mm | 2. | \(0.075\) mm |
3. | \(0.1\) mm | 4. | \(0.15\) mm |
In the CGS system, Young's modulus of a steel wire is \(2\times 10^{12}\) dyne/cm2. To double the length of a wire of unit cross-section area, the force required is:
1. \(4\times 10^{6}\) dynes
2. \(2\times 10^{12}\) dynes
3. \(2\times 10^{12}\) newtons
4. \(2\times 10^{8}\) dynes
A force \(F\) is needed to break a copper wire having radius \(R.\) The force needed to break a copper wire of radius \(2R\) will be:
1. | \(F/2\) | 2. | \(2F\) |
3. | \(4F\) | 4. | \(F/4\) |
Steel and copper wires of the same length and area are stretched by the same weight one after the other. Young's modulus of steel and copper are \(2\times10^{11} ~\text{N/m}^2\) and \(1.2\times10^{11}~\text{N/m}^2\). The ratio of increase in length is:
1. | \(2 \over 5\) | 2. | \(3 \over 5\) |
3. | \(5 \over 4\) | 4. | \(5 \over 2\) |
Two wires of copper having length in the ratio of \(4:1\) and radii ratio of \(1:4\) are stretched by the same force. The ratio of longitudinal strain in the two will be:
1. | \(1:16\) | 2. | \(16:1\) |
3. | \(1:64\) | 4. | \(64:1\) |
On applying stress of \(20 \times 10^{8}~\text{N/m}^2\), the length of a perfectly elastic wire is doubled. It's Young’s modulus will be:
1. | \(40 \times 10^{8}~\text{N/m}^2\) | 2. | \(20 \times 10^{8}~\text{N/m}^2\) |
3. | \(10 \times 10^{8}~\text{N/m}^2\) | 4. | \(5 \times 10^{8}~\text{N/m}^2\) |
The ratio of lengths of two rods \(A\) and \(B\) of the same material is \(1:2\) and the ratio of their radii is \(2:1\). The ratio of modulus of rigidity of \(A\) and \(B\) will be:
1. | \(4:1\) | 2. | \(16:1\) |
3. | \(8:1\) | 4. | \(1:1\) |