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Static Friction and Gravity

  1. Mar 31, 2010 #1
    Hey guys first time posting and I have a really frustrating question. Is there static friction when the force of gravity is pulling an object straight against a surface. I believe that there is none because (i don't know if I'm wording this right) the friction is equal to the normal of the collision. Let's say you have a 20lb object on perfectly level ground. The only forces acting on the object would be gravity and the reaction force of the ground keeping the object up. Am I right about this. Looking forward to some answers. Thanks.
  2. jcsd
  3. Mar 31, 2010 #2


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    Yes those will be the only two forces acting. Friction is only present when there is motion between them mass and the surface.
  4. Mar 31, 2010 #3
    Thank you so much for comfirming that. I had a really long debate with a friend about this and he refused to believe it was true. Now I know how to prove it to him. Thanks for the help.
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