I want to know how the Ff from the 2nd line turns into Fn in the third

Also how the third line turns into the final equation that is circled. I can't figure out where the extra Fn went.

http://i.imgur.com/Sm4LDXI.jpg

Can we know more about the problem? The Ff to Fn could just be a simple error with formulas.

The third line you should be able to factor out a Fn, give me a second to upload a picture.

e; can't solve it, not sure where that static friction coefficient came into play.

This post was edited by Blizzardboy on Dec 8 2014 10:28pm

Afaik this is a centripetal force problem on an incline.

Ff is Fn * mu, but it wasn't written in the middle equations, just thrown in @ the end.

Ignore FBD in top right.
Use FBD on right side.



This post was edited by Dontrunaway on Dec 8 2014 11:35pm

Pretty simple solve... Factor F_n out on right side and solve for it by dividing by (sin(19.4)+cos(19.4)) to get solution.

Can't forget mu.

Indeed forgot to type that in :0 typing math on phone made me miss that one lol but you had a nice picture of solution for him already, was just trying to explain steps for him.