Final answer:
The coefficient of performance (COP) of a refrigerator can be calculated using the formula: COP = heat removed from the cold reservoir / work input. In this case, the COP is 3.
Step-by-step explanation:
The coefficient of performance (COP) of a refrigerator can be calculated using the formula:
COP = heat removed from the cold reservoir / work input
In this case, the heat removed from the cold reservoir is 60 J and the work input is 20 J. So, the COP of the refrigerator is:
COP = 60 J / 20 J = 3