Answer:
The final temperature of the water is 23.92°C.
Explanation:
Given that,
A heater in a hot water tank gives off 20,000 kJ per hour.
For 1 hour or 60 minutes, heat is 20,000 kJ
For 90 minutes,
[tex]Q=\dfrac{20000}{60}\times 90\\Q=30000\ kJ[/tex]
Mass, m = 450 kg or 450000 grams
Initial temperature, [tex]T_i=8^{\circ} C[/tex]
We need to find the final temperature of the water. We know that the specific heat capacity of water is 4.186 J/g- °C
Heat is given by :
[tex]Q=mc\Delta T\\\\Q=mc(T_f-T_i)\\\\T_f=\dfrac{Q}{mc}+T_i\\\\T_f=\dfrac{30000\times 10^3}{450000\times 4.186}+8\\\\T_f=23.92^{\circ} C[/tex]
Hence, the final temperature of the water is 23.92°C.
