Answer
a. $3.6\times10^7J$
b. 63 minutes
Work Step by Step
Use equation 14–2. One liter of water has a mass of 1 kg.
a. $Q=mc\Delta T=(245kg)(\frac{4186J}{kg\cdot C^{\circ}})(45^{\circ}C-10^{\circ}C)=3.6\times10^7J$
b. Power is the rate at which energy is used.
$$P=9500\frac{J}{s}=\frac{3.6\times10^7J }{t}$$
Solve for t = 3778s, or about 63 minutes.