A rocket moves forward by expelling gases backward. This is an application of:

1. Newton's third law states that every action has an equal and opposite reaction. 2. The rocket exerts a force on the gases pushing them backward. 3. The gases in turn exert an equal and opposite force on the rocket pushing it forward. 4. The two forces act on different bodies, so they do not cancel. 5. So rocket propulsion demonstrates Newton's third law. _Source: Selina Concise Physics ICSE Class 9, Ch 3 'Laws of Motion' (aplustopper.com extract)_