• Question: If you are in space, just floating around (as you do) would you be moving out of control or would you just be stuck and not move at all?

    Asked by smileysoph to Adam, Catherine, Karen, Leila, Nazim on 15 Mar 2012.
    • Photo: Leila Battison

      Leila Battison answered on 15 Mar 2012:

      Presumably you got into floating around by jumping out or being thrown out a spaceship in the first place, so you would have some force of motion to begin with, even if it was small.

      One of the physical laws of motion says that your speed and direction will stay the same, unless something else comes along to change it. So you would be floating in one direction until something hit you! Because most of space is a vacuum, even flailing your arms around like an idiot won’t do any good, because there are no air molecules to get friction against!

    • Photo: Adam Stevens

      Adam Stevens answered on 15 Mar 2012:

      If you’re just on your own in space, which is very likely, you would just float around in whatever direction you were travelling when you started.

      In fact, when astronauts go on a space walk they either hang on to the space station (and are tied on just in case they let go) or they have little jetpacks!

      The furthest away from a spacecraft anyone has ever gone is in this picture:

      So the jetpack allows you to move in any direction, but I reckon it would have still been pretty scary.

      In the days before the Apollo program the astronauts tried out a gun that fired a jet so they had to point the gun in the opposite direction to the one they wanted to move in!

    • Photo: Karen Masters

      Karen Masters answered on 18 Mar 2012:

      Great question. Being in space demonstrates really well our basic laws of motion (called Newton’s laws). Often on Earth they’re not obvious because there are all these hidden forces like friction and air resistance hiding from us what’s really going on. Newton figured it out though and his three laws are:

      1. In order to chance the speed or direction of an objects motion a force has to be applied.
      2. If an object pushes on something that thing pushes back equally and opposite.
      3. The more mass an object has the more force is needed to change its speed or direction of motion.

      So in space to change your own motion you need to find a force to act on you (law 1). That means if your moving you’ll keep moving until you hit something (or do something), and if you’re not moving you could be a bit stuck. But, using (2) – if you push on something, it’ll push on you and you can move. If you have nothing to push on you can get a similar effect by throwing things – so in space you could propel yourself along by throwing M&Ms (or anything) backwards…..

      And the heavier you are (more massive) the more force you’d need to get going. Astronauts sometime notice this when they “carry” massive things in space. They can carrying huge weights, but then they have a really hard time stopping them moving when they’re done. It’s something called inertia.

      Great question again. Hope you liked my explanation of Newton’s Laws. 🙂

    • Photo: Nazim Bharmal

      Nazim Bharmal answered on 18 Mar 2012:

      There is no friction in space, so once you start moving, you keep going in that direction unless some other force acts on you (like gravity). If you were in a space suit, you usually have little thrusters to help you move around, so you could probably control where you are going using them.

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