One of the First Atomic Bombs Released Energy Equivalent to That

Short Answer

One of the first atomic bombs released energy equivalent to that of 20,000 tons of TNT explosive. How much mass was converted to energy by this explosion, given that 1000 tons of TNT produce $4.3 \times 10 ^ { 12 } \mathrm {~J}$ of energy. Incidentally, modern $\mathrm { H }$ -bombs have energy yields 1000 times as much! $( c = 3.0 \times 10^8 \mathrm {~m} / \mathrm { s } )$