Manhattan Project Explained
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Covers Nuclear Fission: The Physics, Enriching Uranium: The Engineering Problem, Building the Bomb: Design & Assembly and more.
“Manhattan Project Explained” is a 4-lesson course at Teen level, created with soclever, a personal AI teacher. Each lesson takes a few minutes and ends with a check-in question; finish the curriculum and you can take a certificate test to earn a diploma. Try the first lesson without an account — or make your own course on any topic.
What you'll learn
- Nuclear Fission: The Physics. You just fired a neutron at a uranium-235 nucleus. It smashes in, destabilizing the atom.
- Enriching Uranium: The Engineering Problem. How do you separate two things that are chemically identical? Natural uranium is 99.3% U-238 and 0.7% U-235. Both are uranium atoms—same number of protons, same chemical behavior.
- Building the Bomb: Design & Assembly. The hardest part of building an atomic bomb wasn't splitting atoms—it was getting them to split at the same time, in the same place, fast enough to matter.
- The Decision to Use It. By summer 1945, the atomic bomb was finished.
Lesson 1: Nuclear Fission: The Physics
You just fired a neutron at a uranium-235 nucleus. It smashes in, destabilizing the atom. The nucleus splits—breaks apart into two smaller fragments, plus a couple of extra neutrons burst free.
Here's what matters: those fragments are lighter than the original uranium atom. That missing mass didn't vanish. It converted into energy, according to Einstein's equation E=mc². Since the speed of light (c) is enormous, even a tiny bit of mass releases staggering amounts of energy—heat, radiation, motion. One uranium-235 nucleus splitting releases about 200 million electron volts.
Now the two freed neutrons? They slam into nearby uranium atoms. Each collision splits another nucleus, which releases two more neutrons. Those hit two more atoms. Two becomes four becomes eight becomes sixteen. This is nuclear fission—a chain reaction.
One split atom alone is nothing. But in a lump of enriched uranium, billions upon billions of atoms are packed close. Start a chain reaction in that mass and you get an explosion of uncontrollable heat in microseconds. That's the physics the Manhattan Project exploited. The scientists didn't invent fission—they harnessed it, figured out how to compress enough uranium-235 into one place, fast enough, so the chain reaction would spiral before the material blew itself apart. Control the geometry and timing, and you get a weapon of unprecedented destructive power from pure physics.
Questions this course answers
What happens when a uranium-235 nucleus is hit by a neutron?
It smashes in and destabilizes the atom, causing the nucleus to split into two smaller fragments plus a couple of extra neutrons.
How did engineers separate U-235 from U-238 during the Manhattan Project?
They turned uranium into a gas and shot it through a barrier with microscopic holes, letting the lighter U-235 atoms bounce through slightly more often than the heavier U-238.
What was the gun method used in the Manhattan Project?
It treated the bomb like artillery by firing one piece of uranium-235 down a barrel into another piece at extreme speed to compress them into a single critical mass.
Why did President Truman and his advisors decide to use the atomic bomb?
They believed the atomic bomb would force Japan's surrender without a costly ground war and save American lives.
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