Gce Model Questions Vol1 2025 Physics Question 8

A 0.250 kg block of aluminium (specific heat capacity c₁ = 900 J kg⁻¹ K⁻¹) at 25 °C is placed in thermal contact with a 0.500 kg block of copper (c₂ = 385 J kg⁻¹ K⁻¹) initially at 80 °C. The two blocks are insulated from the surroundings and allowed to reach thermal equilibrium. Afterwards, the combined metal system is placed in a water bath containing 2.00 kg of water (c_w = 4186 J kg⁻¹ K⁻¹) at 20 °C, the whole arrangement being insulated from the environment. Specific heat capacities are taken as constant over the temperature range. The experiment is then repeated, but the aluminium block is coated with a thin layer of oil that provides a thermal resistance R_th = 0.02 K W⁻¹. The surface area of the aluminium block in contact with the water is 0.015 m². For steady‑state heat flow during equilibration with the water bath, the overall heat‑transfer coefficient can be approximated by h = 1 / R_th.