BITSAT2016PhysicsMechanical Properties of SolidsActual
Two wires are made of the same material and have the same volume. However wire 1 has crosssectional area A and wire 2 has cross-sectional area 3 A . If the length of wire 1 increases by x on applying force F , how much force is needed to stretch wire 2 by the same amount?
Options
- A4 F
- B6 ~F
- C9 F
- DF
Correct answer
C. 9 F
Step-by-step solution
As shown in the figure, the wires will have the same Young's modulus (same material) and the length of the wire of area of crosssection 3 A will be / 3 (same volume as wire 1 ). For wire 1, Y= F / A x / For wire 2, Y= F^ / 3 A x /( / 3) From (i) and (ii) , F A x = F^ 3 A 3 x F^ =9 F