Bouyancy is balance of pressure and weight. Rockets Conservation of momentum at work.
Rocket goes in one direction, fuel the other.
Rocket can eventually go faster relative to the ground than the rocket exhaust is leaving the back of the rocket. Gravity declines with separation. Orbitting is combination of circular motion and inward force supplied by gravity. Heat 6.1 Wood Stoves Burning is conversion of chemical pot. In air and water convection is the major heating process.