Exams › JEE Main › Physics

A steel wire has length l and cross-sectional area A. When a certain load is applied, it elongates by 1 cm. If the same load is now applied to another steel wire made of the same material, having twice the length and half the cross-sectional area, what will be its extension?

1. 0.5 cm
2. 2 cm
3. 4 cm
4. 1.5 cm

Correct answer: 4 cm

Solution

Extension dl = F l/(A Y). Doubling length and halving area gives dl' = F(2l)/((A/2)Y) = 4 * F l/(A Y) = 4 * 1 cm = 4 cm.

Related JEE Main Physics questions

• Select the incorrect statement.
• For common metals such as aluminium and copper, which sequence correctly represents the relative magnitudes of the elastic moduli?
• A steel sheet fails under a shear stress of 3.5 × 10⁸ N m⁻². The approximate force required to punch a circular hole of diameter 1 cm through a steel plate 0.3 cm thick is:
• A copper wire of fixed volume V is stretched out to a length l. If a constant force F is applied to this wire and it elongates by Δl, which of the following plots would be a straight line?
• A material has Poisson’s ratio equal to 0.5. When a tensile force is applied to a wire made of this material, its cross-sectional area decreases by 4%. The corresponding percentage increase in its length is:
• A uniform wire of length L and weight W is fixed at its upper end to a point on the roof, and a load of weight W1 is hung from its lower end. If the wire has cross-sectional area s, what is the stress in the wire at a point located 3L/4 above the lower end?

⚔️ Practice JEE Main Physics free + battle 1v1 →