A stainless-steel rod 0.30 m long with cross-sectional area 1.5 cm² connects a heater…
PHYSICS · Subjective · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
A stainless-steel rod 0.30 m long with cross-sectional area 1.5 cm² connects a heater held at 200 °C to a small copper calorimeter cup of mass 80 g containing 50 g of water, both initially at 20 °C. The rod’s thermal conductivity is 16 W/m·°C. While energy is conducted down the rod, the cup–water system loses energy to the surrounding air at a constant rate of 1.5 W. The specific heats are 0.39 J/g·°C for copper and 4.2 J/g·°C for water. Determine the temperature of the water–cup system 60 s after the rod is connected to the heater. Assume the cup and water remain in thermal equilibrium with each other and neglect any change in the surrounding air temperature.