Question

79.Свинцевий брусок за температури 5 °C опускають в посудину, у якій міститься 3 кг окропу. Яка маса бруска, якщо температура в посудині понизилась до 95 °С? Теплообмін з посудиною не враховувати

Answer 1

Відповідь: 5 кг

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c₁ = 140 Дж/(кг*°С)

t₁ = 5 °C

t₂ = 100 °C

m₂ = 3 кг

с₂ = 4200 Дж/(кг*°С)

t = 95 °C

m₁ = ?

Рішення:

Q₁ = c₁m₁(t-t₁)

Q₂ = c₂m₂(t₂-t)

Q₁ = Q₂

c₁m₁(t-t₁) = c₂m₂(t₂-t)

m₁ = c₂*m₂*(t₂-t)/c₁*(t-t₁) = 4200*3*(100-95)/140*(95-5) = 63000/12600 = 5 кг

Answer 2

To calculate the mass of the lead block, we can use the principle of heat exchange. When the lead block is added to the vessel containing 3 kg of water, it will transfer heat to the water until both reach a common final temperature. We can use the equation:

Q1 + Q2 = 0

where Q1 is the heat gained by the water and Q2 is the heat lost by the lead block.

The heat gained by the water can be calculated using the equation:

Q1 = m1 * c1 * ΔT1

where m1 is the mass of water, c1 is the specific heat capacity of water, and ΔT1 is the change in temperature of the water.

The heat lost by the lead block can be