m = 20.0kg, the mass of the block.
c = 1700 J/(kg-°C), the specific heat
ΔT = 25 - 15 = 10 °C = 10 K, the change in temperature.
The change in thermal energy is
[tex]Q = (20.0 \, kg)*(1700 \, \frac{J}{kg-C} )*(10 \, C) = 340 \times 10^{3} \, J[/tex]
Answer: 340 kJ (or 340,000 J)