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Homework Help: Normal Force of an object being pushed

  1. Sep 27, 2012 #1
    You push a 8.00 kg suitcase across a smooth horizontal floor applying a force directed 35.4 degrees below the horizontal. Someone measures the acceleration of the suitcase to be 1.26 m/s2.

    Assuming g = 10.0 m/s2, what is the normal force the ground exerts on the suitcase?

    So is normal friction opposite to gravity always or opposite of total direction?

    Well force of gravity is F=8(10)
    Force horizontal is F=1.26(8)

    Then what? thanks
  2. jcsd
  3. Sep 27, 2012 #2

    Simon Bridge

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    Don't understand the question.

    Friction is along a surface, not normal to it.
    The magnitude of the friction is proportional to the magnitude of the normal force to the surface - the harder you press into the surface the greater the resistance to moving along the surface.

    In this case, part of the applied force is along the surface and part is into the surface.
    Since the object does not move into the surface, there must be a force from the surface acting against the force into the surface to cancel it out. This is usually called "the normal force" - since it acts 90deg to the surface.

    Your free body diagram should show the applied force at an angle, weight pointing down, and the normal force pointing up.
    The sum of these forces should be a net unbalanced force pointing horizontally.

    Hopefully something in there solves your confusion.
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