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A solar water heater can make 100kg water in 5h, the temperature rises 60 degrees Celsius, then how many joules of heat does the water absorb? Regardless of the heat loss, heat these A solar water heater can make 100kg of water within 5h, and the temperature rises by 60 degrees Celsius. How many joules of heat does the water absorb? Regardless of the heat loss, how many kilograms of liquefied gas is needed to heat the water?
Heat absorbed by water: q = cm (t-t0) = 4200 * 100 * 60 = 25200000j
Heat released by LPG: q = MQ
25200000j = m gas * q gas
On the calorific value of liquefied gas Q gas, the topic is to be given, you can calculate the mass of liquefied gas
(1) How many joules of energy is absorbed by heating 100kg water from 25 ℃ to 75 ℃ with solar water heater?
(2) If the gas water heater heats the same water from 25 ℃ to 75 ℃, the gas is completely burned and 60% of the heat is absorbed by the water, how many kg of gas need to be burned? (the calorific value of the gas is 4.2 times 10 of the seventh power J / kg)
Answer: 21000 000j 0833kg
Analysis:
1、
Q suction = C water m △ t
＝4200×100×（75-25）
＝21000 000J
2、
Q suction = 60% Q discharge, Q discharge = MQ
That is: 21000000 = 60% × m × 42000000
The solution is: M = 0.833kg
Solar water heater has the advantages of safety, energy saving and environmental protection. A solar water heater can increase the temperature of 100kg water by 60 ℃ within 5h. If the heat loss is not included, the water heater will absorb solar energy during this period______ J．
Solar energy absorbed by water heater: Q absorption = cm △ t = 4.2 × 103J / (kg ·℃) × 100kg × 60 ℃ = 2.52 × 107j
Excuse me, how many calories or joules does a kilogram of water need for each degree of temperature rise?
1000 calories or 4200 joules per kilogram of water temperature rise
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