A uniform rod of mass \(m,\) having cross-section \(A\) is pushed along its length \((L)\) by means of a force of magnitude, \(F.\) There is no friction anywhere. Ignore the weight of the rod. The longitudinal stress in the rod, at a distance \(L \over 3\) from the left end, is:
         
1. tensile, \(F \over 3A\)
2. compressive, \(F \over 3A\)
3. tensile, \(2F \over 3A\)
4. compressive, \(2F \over 3A\)

Subtopic:  Stress - Strain |
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A large cylindrical piece of a dense solid elastic metal stands on its end as shown in the figure. The metal is uniform and isotropic. The stress in the material as a function of height is shown correctly by:
   
1.   2.
3.  4. 
Subtopic:  Stress - Strain Curve |
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The breaking stress in two wires of different materials \(A,B\) are in the ratio:    \(\frac{S_A}{S_B}=\frac12,\) while their radii are in the ratio:    \(\frac{r_A}{r_B}=\frac12.\) The tensions under which they break are \(T_A\) and \(T_B.\) Then \(\frac{T_A}{T_B}=\)?
1. \(2\)
2. \(\frac14\)
3. \(\frac18\)
4. \(\frac1{2\sqrt2}\)
Subtopic:  Stress - Strain |
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The elastic energy density in a stretched wire is:
1. (stress)2 × strain
2. stress × strain
3. \(\frac12\) × stress × strain
4. stress × (strain)2
Subtopic:  Potential energy of wire |
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Given below are two statements: 
Assertion (A): The stretching of a spring is determined by the shear modulus of the material of the spring.
Reason (R): A coil spring of copper has more tensile strength than a steel spring of the same dimensions.
 
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is false but (R) is true.
4. (A) is true but (R) is false.
Subtopic:  Shear and bulk modulus |
From NCERT
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If two identically shaped rods are joined end to end and compressive forces are applied to the system, the compressive strain will be:
        
1. larger in the rod with a larger Young's modulus
2. larger in the rod with a smaller Young's modulus
3. equal in both the rods
4. negative in the rod with a smaller Young's modulus
Subtopic:  Young's modulus |
 65%
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A wire of cross-section \(A_{1}\) and length \(l_1\) breaks when it is under tension \(T_{1};\) a second wire made of the same material but of cross-section \(A_{2}\) and length \(l_2\) breaks under tension \(T_{2}.\) A third wire of the same material having cross-section \(A,\) length \(l\) breaks under tension \(\frac{T_1+T_2}{2}\). Then,

1. \(A=\frac{A_1+A_2}{2},~l=\frac{l_1+l_2}{2}\)
2. \(l=\frac{l_1+l_2}{2}\)
3. \(A=\frac{A_1+A_2}{2}\)
4. \(A=\frac{A_1T_1+A_2T_2}{2(T_1+T_2)},~l=\frac{l_1T_1+l_2T_2}{2(T_1+T_2)}\)
Subtopic:  Young's modulus |
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When a metal wire elongates by hanging a load on it, the gravitational potential energy is decreased.

1. this energy completely appears as the increased kinetic energy of the block
2. this energy completely appears as the increased elastic potential energy of the wire
3. this energy completely appears as heat
4. none of these
Subtopic:  Potential energy of wire |
From NCERT
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A heavy mass is attached to a thin wire and is whirled in a vertical circle. The wire is most likely to break:

1. when the mass is at the highest point
2. when the mass is at the lowest point
3. when the wire is horizontal
4. at an angle of \(\cos^{-1}(\frac{1}{3})\) from the upward vertical

Subtopic:  Stress - Strain |
 73%
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The length of a metal wire is \(l_1\) when the tension in it is \(T_1\) and is \(l_2\) when the tension is \(T_2.\) The natural length of the wire is:
1. \(\frac{l_{1}+l_{2}}{2}\)

2. \(\sqrt{l_{1} l_{2}}\)

3. \(\frac{l_{1} T_{2}-l_{2} T_{1}}{T_{2}-T_{1}}\)

4. \(\frac{l_{1} T_{2}+l_{2} T_{1}}{T_{2}+T_{1}}\)

Subtopic:  Young's modulus |
 67%
From NCERT
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