What happens after a thruster is fired to push a spacecraft

The thruster pushes small amounts of matter (in the form of a gas or liquid) at very high speed out it's nozzel. Since newtons law states that every action has an equal and opposite re-action, the spacecraft must also experience a push in the opposite direction. This means that the spacecraft accelerates after the thruster is fired. Perhaps the astronauts also hang on to something haha

The magnets are probably damaged or there not strong enough to attached to the refrigerator