How does nuclear fusion produce energy in stars?

Answer 1

Stars operate on nuclear fusion. They operate on E=mc2, turning a little bit of mass into a whole lot of energy. Here's how: Hydrogen (atomic weight 1.008) is pulled into the star by gravity. Four hydrogen atoms get fused together to form one helium atom (atomic weight 4.003). If you look at the atomic weights (4H - 1He) there is a little bit of mass lost!. It turns to energy. Closer to the core of the star, helium fuses into heavier atoms like lithium and boron and carbon and oxygen. But iron is the last atom formed in regular stars by fusion. Fusion stops in all stars eventually as the fuel runs out. Because as smaller atoms get fused into larger atoms, it takes more energy and returns less at each step up until the atoms are iron. Then fusion would require more energy than the fusion could produce. This cooling results in a decrease of the cores' internal pressure that normally balances the force of gravity. Ultimately the star collapses and explodes. This process forms all the higher elements beyond iron. If it's heavy enough, the remnants become a neutron star, or even a black hole. If the star is big enough, it can reach a critical internal pressure that re-ignites the fusion process, but this normally happens suddenly and blows the star apart. Fusion stops in all stars eventually. Because as smaller atoms get fused into larger atoms, it takes more energy and returns less at each step up until the atoms are iron. Then fusion would require more energy than the fusion could return. This cooling results in a decrease of the cores' internal pressure that normally balances the force of gravity. If the star is big enough, it can reach a critical internal pressure that re-ignites the fusion process, but this normally happens suddenly and blows the star apart. == == Fusion is normally refferred to different objects combining.