# Maths / physics

posted by
**Wayne**
.

Calculate the rest mass (In grams) of an object whose rest energy is equal to the energy released by a tonne of tnt the energy liberated by 1 g of tnt = 4kJ

Rest energy = moc 2

1 tonne of tnt equals 10^6 x 4kJ =

4 x 10^6 kJ x (3.0^8)sqrd = 3.6 x 10^23kJ

is this right ?? i cannot work out the grams can anyone help please .. thanks