Total length at 30°C = 120 cm, each rod = 60 cm
αAl=24×10−6/°C, αSteel=1.2×10−5/°C
ΔT=100−30=70°C
ΔLAl=60×24×10−6×70=0.1008 cm
ΔLSteel=60×1.2×10−5×70=0.0504 cm
Total expansion =0.1008+0.0504=0.1512 cm
Final length =120+0.1512=120.15 cm
JEE Main 2026 — Physics Thermodynamics
An aluminium and steel rods having same lengths and cross-sections are joined to make total length of 120 cm at 30∘C. The coefficient of linear expansion of aluminium and steel are 24×10−6/∘C and 1.2×10−5/∘C, respectively. The length of this composite rod when its temperature is raised to 100∘C, is ____ cm.
Held on 21 Jan 2026 · Verified 6 Jul 2026.
120.20
120.15
120.06
120.03
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