| #2 Energy is the ability to do work. (Eg. An object with kinetic energy that undergoes a collision, produces a force and therefore work {Work = Force times displacement}, and potential energy has the ability to do work obviously)
#3. A nuclear chain reaction takes place as a result of atoms being bombarded with neutron, followed by the atoms breaking down, releasing energy along with more neutrons which bombard the next atoms in the series which continues the reaction. It is therefore stopped by inserting control rods of a certain material which absorb neutrons and consequently stop the chain reaction. |