Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Question about momentum

  1. Dec 19, 2009 #1
    I can't seem to wrap my head around this. Perhaps you can help:

    Let's say I've managed to accelerate a mass to 1/2c.
    Now, I wish to get that mass going faster, BUT, the newly applied force is not enough to do this.

    What then happens to the "insufficient" applied energy? Is it absorbed, reflected, dissipated, etc...?

    Last edited: Dec 19, 2009
  2. jcsd
  3. Dec 19, 2009 #2


    Staff: Mentor

    What do you mean? If you apply a force the object will accelerate and the energy will be equal to the force times the distance.
  4. Dec 19, 2009 #3

    Thank you for your interest/reply.

    If the force is unable to further accelerate the mass(by virtue of that force being weaker than required to overcome inertia) what happens to the applied force?

    It is my understanding(perhaps wrong) that an applied force MUST be sufficient enough to overcome the inertia of the mass or the mass will NOT accelerate.
  5. Dec 19, 2009 #4


    Staff: Mentor

    This is a misunderstanding. Any net force, no matter how small, will result in an acceleration. If the force is very small relative to the mass then the acceleration will be correspondingly small, but it will still be there.

    You may be thinking of static friction, where you have to apply a force greater than the static friction force in order for there to be a net force so that the object can start moving.
  6. Dec 19, 2009 #5
    OK. Thank you so much.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook