Answer:
106.24 kJ.
Explanation:
Given that,
Mass of sample of sand, m = 8 kg
Specific heat of sand, c = 664 J/kg-°C
The temperature changes from 20° C to 40° C. We need to find the change in thermal energy. It is given by :
[tex]Q=mc\Delta T\\\\Q=8\times 664(40-20)\\\\=106240\ J\\\\=106.24\ kJ[/tex]
So, the change in thermal energy is 106.24 kJ.