Which principle explains how a balloon propels air when released?

• A. Bernoulli's principle
• B. Archimedes' principle
• C. Newton's third law states: for every action there is a reaction
• D. Charles' Law

Answer: (C)

When the balloon releases, it spits air out the back. Newton's third law says that for every action there is an equal and opposite reaction. The action here is the fast-moving air rushing backward; the reaction is the balloon pushed forward, creating forward thrust. The amount of thrust depends on how much air is expelled and how fast it leaves the balloon.

This isn’t Bernoulli’s principle, which deals with pressure differences from flow over surfaces; nor Archimedes’ principle, which is about buoyancy in a fluid; nor Charles’ Law, which relates gas volume to temperature. The propulsion in this scenario comes from action and reaction.