A wire of length \(L\), area of cross section \(A\) is hanging from a fixed support. The length of the wire changes to \(\mathrm{L}_1\)when mass \(M\) is suspended from its free end. The expression for Young's modulus is:
1. | \(\frac{{Mg(L}_1-{L)}}{{AL}}\) | 2. | \(\frac{{MgL}}{{AL}_1}\) |
3. | \(\frac{{MgL}}{{A(L}_1-{L})}\) | 4. | \(\frac{{MgL}_1}{{AL}}\) |
Two wires are made of the same material and have the same volume. The first wire has a cross-sectional area \(A\) and the second wire has a cross-sectional area \(3A\). If the length of the first wire is increased by \(\Delta l\) on applying a force \(F\), how much force is needed to stretch the second wire by the same amount?
1. | \(9F\) | 2. | \(6F\) |
3. | \(4F\) | 4. | \(F\) |
Copper of fixed volume \(V\) is drawn into a wire of length \(l.\) When this wire is subjected to a constant force \(F,\) the extension produced in the wire is \(\Delta l.\) Which of the following graphs is a straight line?
1. \(\Delta l ~\text{vs}~\frac{1}{l}\)
2. \(\Delta l ~\text{vs}~l^2\)
3. \(\Delta l ~\text{vs}~\frac{1}{l^2}\)
4. \(\Delta l ~\text{vs}~l\)