The atomic bomb utilizes the energy released by the fission of uranium and plutonium to generate far more destructive power than any conventional explosive. Furthermore, the gamma rays, neutron rays and other radiation released by the explosion cause serious physical damage over aperiod of decades.The bomb dropped on Hiroshima was approximately three meters long and weighed four tons. Because the final bomb was shorter than the initial design, it was dubbed `Little Boy`. The bomb carried about 50 kilograms of uranium 235, but the instantaneous fisshion of less than 1 kilogram released the energy equivalent of 16,000 tons of high-performance explosive.