Step 1: A 0.200 kg copper block heated to 100°C is dropped into a calorimeter containing 0.300 kg of water at 20°C. The final equilibrium temperature is 23.5°C. The calorimeter's water equivalent is W = 0.020 kg. Find copper's specific heat s. Step 2: Heat lost by copper = heat gained by water + calorimeter: m_cu·s·(100 − 23.5) = (m_w + W)·s_w·(23.5 − 20). Step 3: Right side: (0.300 + 0.020) × 4186 × 3.5 = 0.320 × 4186 × 3.5 = 4688 J. Step 4: Left side: 0.200 × s × 76.5 = 15.30·s. Step 5: s = 4688/15.30 ≈ 306 J/(kg·K). Result: s ≈ 306 J/(kg·K), below the accepted 385 J/(kg·K) — the shortfall is heat lost to the air during transfer, the classic systematic error; faster transfer and a lid reduce it.