Question

Heat energy released by water of mass \(3\,\text{kg}\) when it is cooled by \(20^\circ C\) is \((\text{specific heat capacity of water}=4200\,\text{J kg}^{-1}\text{K}^{-1})\)

• A. \(252000\ \text{J}\)
• B. \(420000\ \text{J}\)
• C. \(52000\ \text{J}\)
• D. \(25200\ \text{J}\)

Hint:

Always use: \[ Q=mc\Delta T \] for heat gain or loss when no phase change occurs.

Answer 1

The Correct Option is A

Concept: Heat transferred: \[ Q=mc\Delta T \] where \[ m=\text{mass},\quad c=\text{specific heat capacity} \]

Step 1: Substitute values. \[ m=3\,\text{kg} \] \[ c=4200\,\text{J/kg/K} \] \[ \Delta T=20^\circ C \] Hence, \[ Q=3\times4200\times20 \] \[ Q=252000\ \text{J} \] Therefore, \[ \boxed{252000\ \text{J}} \]