Final answer:
To move in the weightless environment of the ISS, an astronaut can throw an object in the opposite direction they wish to travel, utilizing Newton's third law of motion. Even a minute force can be effective due to the lack of weight. This principle is also employed to measure an astronaut's mass in space by applying a known force and measuring the resulting acceleration.
Step-by-step explanation:
If an astronaut is stuck in the center of the International Space Station (ISS) without anything to push against, they must rely on Newton's third law of motion, which states that every action has an equal and opposite reaction. To move, the astronaut could throw an object in the opposite direction they wish to travel. For example, if they throw a wrench away from their body, they will propel themselves in the opposite direction due to the reaction force.
This is similar to how one would push off a wall to move in a swimming pool, but in the weightless environment of space, even a small force, such as that exerted by a single human hair, can move the astronaut. Additionally, by exerting a force on an object, the astronaut experiences a reaction force, which causes acceleration based on the mass of the astronaut as described by Newton's second law, F=ma. This concept is also used to measure the mass of astronauts in space.