Question

A calorimeter contains $0.2kg$ of water at ${30}^{\circ }C$. $0.1kg$ of water at ${60}^{\circ }C$ is added to it, the mixture is well stirred and the resulting temperature is found to be ${35}^{\circ }C$. The thermal capacity of the calorimeter is

• A. $6300J/K$
• B. $1260J/K$
• C. $4200J/K$
• D. none of these

Answer 1

The correct option is B $1260J/K$

Heat released by hotter component= heat absorbed by cooler component
Let the thermal capacity of calorimeter be C J/K.
Then,$.1\times 4200\times (60-35)=.2\times 4200\times (35-30)+C\times (35-30)$
$\Rightarrow 5C=4200\times 1.5\Rightarrow C=1260$
Hence, thermal capacity is $1260J/K$.