We can use the Einsten's relation which states the equivalence between mass and energy:
[tex]E=mc^2[/tex]
where
E is the energy
m is the rest mass of the object
c is the speed of light
By using this formula and m=2.5 kg, we can find the equivalent energy of the object:
[tex]E=mc^2 = (2.5 kg)(3 \cdot 10^8 m/s)^2=2.25 \cdot 10^{17} J[/tex]