Question

How much thermal energy does a 2 kg steel block (c = 450 J/kg°C) lose when it cools from 300°C to

20°C?

Answer 1

Thermal energy lost = 252,000 J

Step-by-step explanation:

change in thermal energy = mass x specific heat capacity x change in temperature

ΔE = mcΔθ

ΔE = change in thermal energy (J)

m = mass (kg)

c = specific heat capacity (J/kg℃)

Δθ = change in temperature (℃)

ΔE = 2 x 450 x (300-20)

ΔE = 252,000 J

Thermal energy lost = 252,000 J

Answer 2

see below

Step-by-step explanation:

x J / (2 kg * (300-20 C) = 450 J / (kgC)

x = 450 * 2(280) = 252000 J = 252 kJ