1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is the importance of Mass in out of gravity i.e out o?

  1. Feb 28, 2015 #1
    In earth due to gravity if m is greater, greater the force need to move it..but what in case of space where has no gravity ???
  2. jcsd
  3. Feb 28, 2015 #2

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    What makes you think in space there is no gravity? Why does the moon stay in orbit?
  4. Feb 28, 2015 #3
    This attachment might help:

    Attached Files:

  5. Feb 28, 2015 #4
    Thanks to help....it was a silly mistake of my ....
  6. Feb 28, 2015 #5
    ....sorry ...it was a silly mistake of my ....
  7. Feb 28, 2015 #6
    Glad to help, shift the mass from one to the other as you like, re-calculate the orbital data using the attached sheet.

    Attached Files:

  8. Feb 28, 2015 #7


    User Avatar
    Science Advisor

    You seem to be confused about several things. "On earth due to gravity", it is harder to lift an object of greater mass because of its greater weight. On the other hand, it is not necessarily harder to move it horizontally. If there is friction, then the friction force will be proportional to the weight so greater for a more massive object, but if there is no friction, gravity will play no part.

    Either on a frictionless surface or in space, far from any massive object, so that gravitational force is negligible (not 0), we still have inertia, Force is still "mass time acceleration" so a greater force is needed to start (or stop) the motion of a massive object- but not to keep it moving.
  9. Feb 28, 2015 #8


    User Avatar
    Homework Helper
    Gold Member

    Newton's 2nd law F=ma or a=F/m holds everywhere so the greater the mass m is the more force F we have to put in order to achieve the same acceleration a. if we put [itex]F=F_{external}-B [/itex]and since the weight B is reduced in space due to the increased distance from earth we can say we can put less force [itex]F_{external}[/itex] to achieve the same acceleration a, but i feel this is not what we had in our minds when we talk about this.

    However what i believe we had in mind and happens inside a space station or a space shuttle in orbit around the earth is that the gravity from earth acts as a centripetal force rather than a pull down force. Inside a space station you just dont feel the gravitational pull from earth though it exists, so i guess from that, one might get the delusion that gravity doesnt exist in space or that is easier to move things in space.
    Last edited: Feb 28, 2015
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook