Question

what are the reasons the bomb should have been dropped on japan?
PLEASE, PLEASE HELP ME.

Answer 1

The short answer is that the military believed it would save American lives and end the war. After seeing how the Japanese fought nearly to the last man at places like Iwo Jima, Guadalcanal, and Tarawa, and how many casualties were left in the aftermath, American planners felt that an invasion of the Japanese home islands would be horrifically costly. So they picked the option that focused on saving soldiers' lives even if it meant utterly annihilating the enemy to do it. It was either "us or them".

There was a huge debate about this afterwards, of course, especially since the military also had no idea what radiation and fallout would actually do to the survivors in the aftermath.