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Homework Help: Motion after force applied is removed

  1. Apr 14, 2016 #1
    1. The problem statement, all variables and given/known data
    Force is applied to a body from A to B, and then withdrawn.

    Question: What happens after B ?
    1. Will the body keeps accelerating after B ?
    2. Will the body keeps moving with constant velocity after B ?

    Consider both friction and frictionless surface.

    2. The attempt at a solution

    Case1 : Frictionless surface

    1. No. The body stops accelerating because force is removed.
    2. Yes.

    Case2 : Frictional surface
    1. No. The body stops accelerating because external force is removed.
    2. No, body will deccelerate, and this decceleration would be found using frictional force which is now the only force acting on it.
  2. jcsd
  3. Apr 14, 2016 #2
    where lies your own question/confusion?
  4. Apr 14, 2016 #3
    Whether my answer/attempt is right or wrong ?
  5. Apr 14, 2016 #4
    your answer has to be checked by Newton's laws of motion -
    if no net force is acting on the body ,the body will maintain its inertia of rest/motion with uniform velocity.
    so , on that basis your first set of answer is correct

    now you have the iind part that the body is moving on a surface with frictional force acting-
    so you have two forces and the net force will generate the motion - if the applied force is removed the body will not accelerate in forward direction but will be acted upon by the frictional force which acts opposite to motion so the body will decelerate and come to rest after some time.
    so your iind part -answer is also correct
    but if you have the laws in your hand you can be definite about it.
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