Benny wonders why when he presses his finger against a map nothing happens to the map. However, if he presses a thumbtack into the map using
the same force, the tack will probably poke a hole in the map. This is what his friends said was the reason:
Heather: I think it’s because the tack is made of metal.
Steve: I think it’s because your finger has more surface area.
Ashia: I think it’s because your finger is warm.
With whom do you agree most?
Explain

it is the minimum amount of material needed to sustain a fission reaction.

critical mass is the minimum amount of fissionable material that must be assembled for a sustained fission reaction to take place. although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction. if the conditions are such that the neutrons are lost at a faster rate than they are formed by fission, the chain reaction will not be self-sustaining.   at the point where the chain reaction can become self-sustaining, this is referred to as critical mass.