Fill in the blanks: A household refrigerator that has a power input of 500 watts and a COP of 2 is to cool eight large watermelons, 5 kg each, to 10°C. If the watermelons are initially at 20°C,...

Extracted text: Fill in the blanks: A household refrigerator that has a power input of 500 watts and a COP of 2 is to cool eight large watermelons, 5 kg each, to 10°C. If the watermelons are initially at 20°C, determine how long will take for the refrigerator cool them. The watermelons can be treated as water whose specific heat is 4.2 KJ/kg-K. hours