Determine the amount of heat required to melt a steel bar weighing 2 kg, taken at its melting temperature.

The amount of energy required to melt a steel bar is calculated using the formula:
Q = λ * m, where λ is the specific heat of fusion of steel (λ = 84 kJ / kg = 84 * 10³ J / kg), m is the mass of steel (m = 2 kg).
Let’s calculate the required amount of energy to melt a steel bar:
Q = λ * m = 84 * 10³ * 2 = 168 * 10³ J = 168 kJ.
Answer: To melt a steel bar, you need to spend 168 kJ of heat.