Frictional force, normal force and coefficient of friction

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Homework Help Overview

The discussion revolves around calculating the frictional force, normal force, and coefficient of friction for a 0.2 kg object on a 35-degree incline. Participants are exploring the dynamics of forces acting on the object in this context.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the normal force using a specific equation but expresses uncertainty about determining the frictional force. Some participants suggest analyzing the forces acting on the object, particularly noting that the block is not accelerating, which implies a balance of forces.

Discussion Status

Participants are actively engaging with the problem, with some providing insights into the relationship between forces on the incline. There is a recognition that the angle of 35 degrees is significant, as it marks the point where gravitational forces begin to overcome friction. No consensus has been reached yet, but the discussion is progressing with various interpretations being explored.

Contextual Notes

There is a mention that the angle of 35 degrees is when the object starts to move down the slope, which may influence the calculations and assumptions regarding static versus kinetic friction.

lisa1991
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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
 
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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.
 
sorry also should have mentioned that 35 degrees is the angle the object starts to move down the slope
 
lisa1991 said:
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

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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