2007 General Studies, all questions
UPSC Prelims 2007 · General Studies
Question 108: Science and Technology
Four wires of the same material and of the dimensions given below are stretched by equal loads separately. Which one of them will be elongated the maximum?
aWire of 1 m length and 2 mm diameter
bWire of 2 m length and 2 mm diameter
cWire of 3 m length and 1.5 mm diameter
dWire of 1 m length and 1 mm diameter
AnswerThe answer is (c).
Under the same load, the elongation of a wire of the same material is proportional to length divided by the square of the diameter (L / d squared). Comparing: (a) 1/4 = 0.25, (b) 2/4 = 0.5, (c) 3/2.25 = 1.33, (d) 1/1 = 1. The 3 m wire of 1.5 mm diameter has the largest value, so it stretches the most.
Why each option is right or wrong
- (a) L/d^2 = 0.25, the smallest.
- (b) L/d^2 = 0.5.
- (c) Correct: L/d^2 = 1.33, the largest.
- (d) L/d^2 = 1, less than option (c).
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2007, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.