Answer
$4.6\times10^6J$ of heat in half an hour.
Work Step by Step
Table 15–2 shows that riding a bicycle at a racing pace requires 1270 watts. According to the problem, that power, exerted for half an hour, is the work input to the heat pump.
$$W=1270\frac{J}{s}(1800s)$$
$COP=\frac{Q_H}{W}$
$$Q_H=W(COP)=(1270watts)(1800s)(2.0)=4.6\times 10^6J$$