Frictional force, normal force and coefficient of friction

  • Thread starter lisa1991
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  • #1
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Homework Statement



Calculate the frictional force, normal force and coefficient of friction for an 0.2kg object that is lying on a 35 degree incline.


Homework Equations



Ff= u x Fn
F= m x a

The Attempt at a Solution



I managed to get FN= m x a x cos# = -9.81 x 0.2 x cos35 = 1.61 N

I have no idea how to get Ff, but when I work that out I will be able to work out coefficient (u). Thanks for any help
 

Answers and Replies

  • #2
tms
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Since the block is not accelerating, the net force must be zero. Look at all the forces, and find their components along the incline and normal to it.
 
  • #3
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sorry also should have mentioned that 35 degrees is the angle the object starts to move down the slope
 
  • #4
NascentOxygen
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sorry also should have mentioned that 35 degrees is the angle the object starts to move down the slope
Hi lisa1991! http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

At 35° the component of gravity overcomes friction, so the forces are equal and opposite. Draw a diagram showing the incline and the direction of the forces involved.
 
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