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Determine the value of the coefficient of friction

  1. Nov 25, 2006 #1
    I have this physics lab due on friction.

    Aim: To determine the value of the coefficient of friction by measuring sliding friction of a block on the table and carrying the normal force.

    I need a detailed explanation on why the frictional force is increased when the mass is increased. Does gravity play a role in this? Thanx in advance.
  2. jcsd
  3. Nov 25, 2006 #2
    I'll help you if you show some work to see where your problem is...
  4. Nov 26, 2006 #3
    because sliding frictional force equals coefficent times normal force,
    when the mass of an object increases , then it will brings a greater graivity to the object which in turn may increas the normal force. so the frictional force will become greater when mass is increased
  5. Nov 26, 2006 #4
    I need to find the coefficient of friction. Ff= µFn from the following data:

    Normal Weight(N)

    Average Pull force


    The normal force is the weight. Does to the Anyone knows how to do it...!! reply ASAP
  6. Nov 27, 2006 #5
    actually the pull force has no relationship to coeffficience but we can find out the sliding force when i pull the object along with a constant velocity by reading the pull force applied. so if the data of average pull force comes from the experiments in which you pull the objects with constant velocity, then you can get the coefficience by the equation
    F(sliding force)= F(pull force)=u N
    such as 0.2= u2.5 u=0.08
    0.4=u4.5 u= 0.89 。。。。。。。
    then you can try to find out the average value of u
    that is the solution

    Notice: did you do the experiment on a horizental surface ? it has to be on the horizental surface otherwise the weight doesn't equal to normal force
  7. Nov 27, 2006 #6


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    Notice that it is also important to ensure that the 'pulling' force is parallel to your surface; otherwise, a component of the 'pulling' force would act to reduce the normal reaction force.
  8. Nov 27, 2006 #7
    Thanx for the help everyone. Yup the experiment was done on a horizontal surface!
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