Answer:
5700 BTU
Step-by-step explanation:
Data provided in the question:
1 kwh = 3400 BTU’s
1 gallon = 8 pounds of water
Initial temperature = 50°F
Final temperature = 100°F
Water used by dishwasher = 10 gallons
Electrical energy used = 0.5 kwh
Now,
Water used in pounds = 10 × 8 = 80 lb
Total electrical energy used in BTU = 0.5 × 3400 BTU [ as 1 kwh = 3400 BTU]
Total electrical energy used in BTU = 1700 BTU
Energy used by water = Water used by dishwasher × Change in temperature × Specific heat of water
[ Specific heat of water = 1 BTU / °F.lb ]
Thus,
Energy used by water = 80 × 1 × ( 100 - 50 )
= 4000 BTU
Hence,
Total energy used = 1700 BTU + 4000 BTU = 5700 BTU
