# How many degrees a steel bar with a mass of 20 kg should cool down in order to transfer the amount

How many degrees a steel bar with a mass of 20 kg should cool down in order to transfer the amount of 690 kJ to the environment.

Task data: m (weight of the steel bar taken) = 20 kg; Q (the amount of heat transferred by the bar to the environment) = 690 kJ (690 * 10 ^ 3 J).

Reference values: Cc (specific heat capacity of steel) = 460 J / (kg * K).

The desired change in the temperature of the steel bar taken can be expressed from the formula: Q = Cc * m * Δt, whence Δt = Q / (Cc * m).

Calculation: Δt = 690 * 10 ^ 3 / (460 * 20) = 75 ºС.

Answer: The taken steel bar must be cooled by 75 ºС.

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