Q 11-11-017JEE MainAIEEE 2011Easy
$100$ g of water is heated from $30°$C to $50°$C. Ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is $4184$ J/kg K)
Answer: (D) $8.4$ kJ
With negligible expansion, $W \approx 0$ and $\Delta U = Q = ms\Delta T = 0.1 \times 4184 \times 20 \approx 8.4$ kJ.
Solution by Sreeraj P, M.Sc Physics