Assignment:
A heat pump with a COP (coefficient of performance) of 2.8 is used to heat an air-tight house. When running, the heat pump consumes 5 kW of power. If the temperature in the house is 7 degrees Celsius when the heat pump is turned on, how long will it take for the heat pump to raise the temperature of the house to 22 degrees Celsius? Is this answer realistic or optimistic? Explain. Assume the entire mass within the house (air, furniture, etc.) is equivalent to 1500 kg of air.
Provide complete and step by step solution for the question and show calculations and use formulas.