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Why can't gravity be modeled as a frictional force?

  1. Aug 24, 2013 #1
    Hey there, I'm new! :D

    The weight, which is mass according to the gravity, and this scalar force keeps the object on to the ground, and if a force pushes the object horizontally, then why can't be the mass according to the gravity (weight) be modeled as a frictional force resisting the horizontal movement? Of course, a tank requires more force because its mass according to the gravity (weight) is greater than a mobile phone, since its weight absorbs all the movement.

    And also, if the object is sitting on the ground, and that the gravitational force is canceled out by the equal and opposite force by the ground, then WHY do we feel the weight of the object if we put it on our hands?

    Was experimenting with a pendulum, and thought that gravity WOULD stop the motion eventually.

  2. jcsd
  3. Aug 24, 2013 #2
    Gravitational force is a conservative force, and frictional forces are non-conservative.
  4. Aug 24, 2013 #3


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    Science Advisor

    Gravity is not a contact force.
  5. Aug 25, 2013 #4


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    Staff: Mentor

    How effectively does your model predict how the planets move in their orbits under the influence of gravity?
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