Coefficient of friction homework problem

[copyfilew]

Homework Statement

A 10kg mass is released from rest and slides down an incline that makes an angle of 37degrees with the horizontal. The coefficient of friction is 0.4 on the incline. Determine (a) the force of friction acting to oppose the motion, and (b) the acceleration

Homework Equations

Determine (a) the force of friction acting to oppose the motion, and (b) the acceleration

The Attempt at a Solution

I first drew a free body diagram...

N = (m)(g)Cos(37)
N = 75

F = (0.4)(75)
= 30

Is that correct?

 

[Chi Meson]

yes, correct so far. Find a.

 

[pooface]

I am getting normal force as 78.35 N

but your method is correct.

What about part b?

 

[Chi Meson]

I agree with pooface. And that's the first time I have ever said that sentence! 78 N is better.

 

[copyfilew]

To be honest, I have no idea where to go from here. Any hints?

 

[pooface]

calculate the force acting down the slope. then you would the friction acting one way and the force the other way.

Subtract them and get the net force. Then you can use F=ma to find acceleration.