Two wires are made of the same material and have the same volume. However, wire 1 has a cross-sectional area of A, and wire 2 has a cross-sectional area of 3A. If the length of wire 1 increases by Δx on applying force F, how much force is needed to stretch wire 2 by the same amount?
Correct answer: C. 6F
- A. F
- B. 4F
- C. 6F
- D. 9F
Explanation
Force to stretch a wire: F=YAΔL/L. Both wires have the same volume: F'/F = A'/A x L/L' = 3x3 F' = 9F
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