Static friction and kinetic friction

[salmacho]

A chuck is sliding downward an inclined plane with friction. The inclined plane has an angel 26 degrees with the horisontal. At a point the chuck has a velocity 4 m/s. The velocity after 2 seconds goes down to 2 m/s. The g is applied to 9.81 m/s^2.

So from here I need to find the kinetic and static friction. The problem for me is that I don't know where to start. When I try do find Fx and Fy, I need the mass, so which way should I go through?

Thanks! :)

 

[Doc Al]

You won't need the actual mass. Just call it "m" and continue.

What does the problem ask you to find? The coefficient of kinetic friction?

 

[salmacho]

You won't need the actual mass. Just call it "m" and continue.

What does the problem ask you to find? The coefficient of kinetic friction?

The problem wants me to find the coefficient between the chuck and the inclined plane

 

[Doc Al]

The problem wants me to find the coefficient between the chuck and the inclined plane

Good.

(1) Figure out the acceleration.

(2) Draw a free body diagram and then apply Newton's 2nd law.

 

[salmacho]

Good.

(1) Figure out the acceleration.

(2) Draw a free body diagram and then apply Newton's 2nd law.

Where am I doing wrong? Please correct me

https://www.dropbox.com/s/t11rf6c2y5cdgjs/2013-04-21 15.00.59.jpg

 

[salmacho]

Where am I doing wrong? Please correct me

https://www.dropbox.com/s/t11rf6c2y5cdgjs/2013-04-21 15.00.59.jpg

I found the problem. Forgot to multiply cos(theta) with with g. Got the right answer. Thank you soo much! :)

 

[Doc Al]

Where am I doing wrong? Please correct me

Redo your algebra. You dropped a factor of g.

 

[jambaugh]

salmacho,
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