How much heat will an iron block weighing 2 tons transfer when cooled from 30 to 10 degrees Celsius?

The amount of heat that the iron bar will give:
Q = C * m * (tn – tc), where C is the specific heat of iron (C = 460 J / (kg * K)), m is the mass of an iron bar (m = 2 t = 2000 kg), tc is the final temperature iron bar (tк = 10 ºС), tн – the initial temperature of the iron bar (tн = 30 ºС).
Let’s calculate the amount of heat given off by the bar:
Q = C * m * (tн – tк) = 460 * 2000 * (10 – 30) = -18400000 J = -18.4 MJ
Answer: The iron bar will transfer 18.4 MJ of heat.