Question

До ванни,де було 100 л холодної води за температури 9 С,додали 60 л гарячої води за температури 81 С.Після встановлення теплової рівноваги температура води у ванні дорівнювала 35 С.Чи були втрати енергії через теплообмін із навколишнім середовищем?

Answer 1

1)
Холодная вода получила тепло:
Q₁=c*m₁*(t - t₁) = 4200*100*(35-9) = 1,09*10⁷ Дж
2)
Горячая вода отдала  тепло:
Q₂=c*m₂*(t₂ -t) = 4200*60*(81-35) = 1,16*10⁷ Дж

Ответ: Поскольку Q₁ отличается от Q₂, то потери энергии были, и составили:
Q₂-Q₁=(1,16-1,09)*10⁷ = 700 000 Дж

Answer 2

Problem Analysis

We are given that there was 100 liters of cold water at a temperature of 9°C in a bathtub, and 60 liters of hot water at a temperature of 81°C were added. After reaching thermal equilibrium, the temperature of the water in the bathtub was 35°C. We need to determine if there were any energy losses due to heat exchange with the surroundings.

Solution

To solve this problem, we can use the principle of conservation of energy. The total energy before and after mixing the hot and cold water should remain the same.

The energy of an object can be calculated using the formula:

Energy = mass × specific heat capacity × temperature

Let's calculate the energy before and after mixing the water.

Calculation

1. Energy before mixing: - Cold water: 100 liters × 9°C - Hot water: 60 liters × 81°C

2. Energy after mixing: - Total water: 100 liters + 60 liters = 160 liters - Temperature after mixing: 35°C

Now, let's calculate the energy before and after mixing and compare them.

Energy Before Mixing

- Cold water: 100 liters × 9°C = 900 units of energy - Hot water: 60 liters × 81°C = 4,860 units of energy

Total energy before mixing = 900 + 4,860 = 5,760 units of energy

Energy After Mixing

- Total water: 160 liters - Temperature after mixing: 35°C

Total energy after mixing = 160 liters × 35°C = 5,600 units of energy

Conclusion

Comparing the total energy before mixing (5,760 units) with the total energy after mixing (5,600 units), we can see that there is a difference of 160 units of energy. This indicates that there were energy losses due to heat exchange with the surroundings.

Therefore, there were energy losses through heat exchange with the surroundings.

Please note that this calculation assumes that there is no heat loss through the container or other factors that may affect the accuracy of the calculation.