The water cooling system of a vehicle contains 7.2 litres of water. Calculate the rise in water temperature if 1.36 MJ of heat energy are absorbed by the water in the system. Take water = 4200 J/kgK and water has a mass of 1 kg per litre.

Solution:
1. Given:
- Total volume of water = 7.2 litres
- Heat energy absorbed = 1.36 MJ = 1.36 \times 10^6 J
- Specific heat capacity of water = 4200 J/kgK
- Density of water = 1 kg/L (so 7.2 litres of water has a mass of 7.2 kg)

2. Use the formula for specific heat:
- Q = m \cdot c \cdot \Delta T, where:
* Q is the heat energy absorbed (J)
* m is the mass of water (kg)
* c is the specific heat capacity (J/kgK)
* \Delta T is the change in temperature (K)

3. Rearrange the formula to solve for \Delta T:
- \Delta T = \frac{Q}{m \cdot c}

4. Substitute the known values into the formula:
- \Delta T = \frac{1.36 \times 10^6}{7.2 \times 4200}

5. Calculate:
- \Delta T = \frac{1.36 \times 10^6}{30240}
- \Delta T \approx 44.97 K

6. The rise in water temperature is:
\Delta T \approx 44.97 K