Consider an object placed in space, where there is no gravity. What is the amount of force needed to move the object by one unit length?

How does that relate to the mass of the object and the time spent?

  • $\begingroup$ Any force applied to an object will result in acceletration with no friction see Newton's 2nd law where F = ma: have a look at physicsforums.com/threads/… $\endgroup$
    – spk578
    Commented Dec 23, 2015 at 10:19

1 Answer 1


That depends on how much time you want to spend. Space is frictionless, you could move a planet by applying a force of 1 N. It would just take a very long time for the planet to move 1 m in response to that force.

Because space is frictionless, you can use basic physics to calculate the information you need. $F=ma$, and from $a$ you can derive the object's speed and position over time.

  • $\begingroup$ Here I have doubt, How to calculate mass in space? $\endgroup$
    – Ayyappan
    Commented Dec 23, 2015 at 10:21
  • 1
    $\begingroup$ Since your mass is likely changing in most cases, it is often better to use F = dP/dt where P is the object's momentum (mass x velocity). $\endgroup$
    – Erik
    Commented Dec 23, 2015 at 10:23
  • 3
    $\begingroup$ @Ayyappan: the mass of an object in space is the same as the mass of an object on Earth. Only its weight can be different. en.wikipedia.org/wiki/Mass_versus_weight $\endgroup$
    – Hobbes
    Commented Dec 23, 2015 at 10:25

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