2012 · Q6
An iron rod of 1 cm diameter and 8 cm length is drawn into a wire of 18 m length with uniform thickness. The thickness of the wire would be :
General Mental Ability, Quantitative Aptitude and StatisticsTime, work and measurement
- A1/21 cm
- B1/18 cm
- C1/15 cm
- D1/12 cm
Explanation
The rod's volume is conserved when drawn into wire: π(0.5)² × 8 = πr² × 1800, using 18 m = 1800 cm. This gives r² = 2/1800 = 1/900, so r = 1/30 cm. The thickness is the diameter, 2r = 1/15 cm. Options like 1/18 or 1/21 cm do not satisfy volume conservation.