Hiroshima’s bomb was Little Boy, which contained 64 kg of uranium, which at 19.1 g/cm^3 would be about 3.3 liters, significantly larger than a cricket ball.
But Nagasaki’s Fat Man used about 6.2 kg of plutonium, which has roughly the same density as uranium, although the implosion mechanism to initiate the chain reaction compressed it to about half the volume. So that’s closer to a cricket ball.
But also to add even more nuance, the plutonium in Fat Man used a uranium tamper to reflect neutrons, and estimates are that about 30% of the explosion yield was due to fission of the uranium too. So it’s hard to really draw the line on what was or wasn’t the “explosive” in that bomb.
Hiroshima’s bomb was Little Boy, which contained 64 kg of uranium, which at 19.1 g/cm^3 would be about 3.3 liters, significantly larger than a cricket ball.
But Nagasaki’s Fat Man used about 6.2 kg of plutonium, which has roughly the same density as uranium, although the implosion mechanism to initiate the chain reaction compressed it to about half the volume. So that’s closer to a cricket ball.
But also to add even more nuance, the plutonium in Fat Man used a uranium tamper to reflect neutrons, and estimates are that about 30% of the explosion yield was due to fission of the uranium too. So it’s hard to really draw the line on what was or wasn’t the “explosive” in that bomb.