85. An iron rod of length 2m and cross section area of , stretched by 0.5 mm, when a mass of 250 kg is hung from its lower end. Young’s modulus of the iron rod is
(a) 19.6×1010 N/m2 (b) 19.6×1015 N/m2
(c) 19.6×1018 N/m2 (d) 19.6×1020 N/m2
Answera-a
(6)