# Conveting Mass Into Energy Problem

1. Homework Statement
The annual energy requirement of the USA is of the order $$10^20$$ J. If we could find a 100% efficient process that could change matter into energy, how many kilograms of material would be needed to meet this requirement?

2. Homework Equations
$$E = mc^2$$

3. The Attempt at a Solution

Well, i simply sub $$10^2^0$$ in to $$E = mc^2$$
And i obtain, $$\frac{10^2^0}{(3.0*10^8)^2}$$
then $$m=11,111.1111$$

Is this correct? It looks to me like too simple a question, since this is the last question of my tutorial.

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