Saw a comment on a Youtube video in which the author expressed his/her skepticism of the space program and wondered how an EMU and a space shuttle could maintain the same orbit. He/she argued that this would be because of the difference in momentum (akin, apparently, to throwing something out of a car window. :facepalm:
Momentum is simply the product of an object's velocity and mass, expressed in terms of the energy required for an object of a certain mass to achieve a certain velocity. Once at that velocity in the near-vacuum of LEO (and the Shuttle/astronauts achieve orbital velocity as a system), the difference in momentum does
not affect their orbits. Their velocity is identical or very similar, and any substantial difference resulting from atmospheric drag at that altitude would take weeks/months to have any non-negligible effect on either body (which is why the ISS is boosted occasionally and satellites can decay).
In the near-vacuum of LEO, the inertia of an object will carry it on a vector tangential to its circular motion, with Earth's gravity pulling it toward the center (i.e. it orbits). Newton's first law indicates that this forward motion would continue until being acted upon by an external force (presumably, atmospheric drag). At the altitude of Shuttle flights and the ISS, this force is so low that it does not make a short-term difference as indicated above. If the physics were such that this commenter suggests, g-forces would be detectable by astronauts in the Shuttle as the atmospheric drag (which, again, is negligible in the short-term at this altitude) acted on the craft, thus pushing them "downward" in the craft as it moved relative to them; this is what happens during reentry, but not to any noticeable degree at LEO.
Not to mention the fact that a car is under power at the Earth's surface when something is thrown out the window while the object thrown isn't (and the air resistance is magnitudes greater). When travelling at orbital velocity, the object is in "free fall" because it is moving faster in the horizontal than it can fall in the vertical, to put it simply.
A lesson for the kids: physics always wins.
</physicsrant>