74. A wire of cross-sectional area is
A wire of cross-sectional area is 3mm2 first stretched between two fixed points at a temperature of 20°C. Determine the tension when the temperature falls to 10°C. Coefficient of linear expansion α=10-5 °C-1 and Y=2×1011 N/m2
(a) 20 N (b) 30 N
(c) 60 N (d) 120 N
Answer-c
(31)