NTA Abhyas JEE Main2020PhysicsMechanical Properties of SolidsPractice
When a metallic wire is held under a tensile force F 1 , the length of the wire is L 1 . If the force is changed to F 2 , the length of the wire is L 2 . The original length L of the wire is
Options
- AL 1 F 1 + L 2 F 2 F 1 + F 2
- BL 2 - L 1 F 1 + F 2
- CF 1 L 2 - F 2 L 1 F 1 - F 2
- DF 1 L 1 - F 2 L 2 F 1 - F 2
Correct answer
C. F 1 L 2 - F 2 L 1 F 1 - F 2
Step-by-step solution
F ∝ d l F 1 ∝ L 1 - l ⇒       ( 1 ) F 2 ∝ L 2 - l ⇒     ( 2 ) F 1 F 2 = L 1 - l L 2 - l F 1 L 2 - F 1 l = F 2 L 1 - F 2 l F 1 - F 2 l = F 1 L 2 - F 2 L 1 l = F 1 L 2 - F 2 L 1 F 1 - F 2