$17\mathrm{.}119.$ An engineer is developing an electric water heater to pro$-$

vide a continuous supply of hot water. One trial design is shown

in Fig. $17\mathrm{.}34.$ Water is flowing at the rate of $0\mathrm{.}500k\frac{g}{m}in,$ the

inlet thermometer registers $18\mathrm{.}0C,$ the voltmeter reads $120V,$

and the ammeter reads $15\mathrm{.}0$ A $[$corresponding to a power input

of $(120V)(15\mathrm{.}0A)=1800W.($a$)$ When a steady state is

finally reached, what is the reading of the outlet thermometer?

$($b$)$ Why is it unnecessary to take into account the heat capacity

$mc$ of the apparatus itself?

Figure $17\mathrm{.}34$ Problem $17\mathrm{.}119.$