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 |
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.
2.
3.
4.
The Young's modulus of steel is twice that of brass. Two wires of the same length and of the same area of cross-section, one of steel and another of brass are suspended from the same roof. If we want the lower ends of the wires to be at the same level, then the weight added to the steel and brass wires must be in the ratio of:
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 )
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 2×1012 dyne/cm2. To double the length of a wire of unit cross-section area, the force required is:
1. 4×106 dynes
2. 2×1012 dynes
3. 2×1012 newtons
4. 2×108 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 |