A system S receives heat continuously from an electrical heater of power $10\,\text{W}$. The temperature of S becomes constant at $50°\text{C}$ when the surrounding temperature is $20°\text{C}$. After the heater is switched off, S cools from $35.1°\text{C}$ to $34.9°\text{C}$ in $1$ minute. The heat capacity of S is