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Homework Help: What is and how do we derive force (F) opposite the force of friction (Ff)?

  1. Oct 7, 2007 #1
    Sum of all Forces= Force - Force of Friction

    We have Formulas to use in our physics test for an object on an inclined plane w/ friction: Sum of all Froces= F-Ff,
    Sum of all Forces=ma,
    a=(Sum of all Forces)/m
    and Sum of all Forces=(mg)sin(theta)-Uk(mg)cos(theta)

    We need to know how to derive F (not the sum of forces "F" but the F that is minus Force of friction) if we are only given mass, theta, and coefficient of friction. also We wish to know the difference between weight, mass, mass*gravity, the Normal Force, and Newtons.
  2. jcsd
  3. Oct 7, 2007 #2


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    Staff Emeritus
    Science Advisor

    Well - the relationship between force, mass and acceleration is F = ma.

    One measures acceleration, then calculates force.

    Weight is simply m*g or mass times the acceleration of gravity, and is a force. Normal means perpendicular to a surface in the usual context.

    Is the weight moving or not?

    If static, i.e. then friction is proportional to the normal force of the mass on the surface.

    If moving at constant velocity, what does that imply?

    If the mass is acceleration, what does that imply?
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