Se da:
α=30°
n=60%=0,6
u=?
Formule:
[tex]n= \frac{Lu}{Lc}\\
n= \frac{mgh}{Fl}\\
n= \frac{mg}{F}*sin \alpha \\
n= \frac{mg}{Gn+Ffr}*sin \alpha \\
n= \frac{mg}{G*sin \alpha +uN}*sin \alpha\\
n= \frac{mg}{G*sin \alpha +u*G*cos \alpha }*sin \alpha \\
n= \frac{mg}{mg(sin \alpha +u*cos \alpha )}*sin \alpha\\
n= \frac{sin \alpha }{sin \alpha +u*cos \alpha }\\
\frac{1}{n}= \frac{sin \alpha +u*cos \alpha }{sin \alpha } \\
\frac{1}{n}=1+u*ctg \alpha \\
u*ctg \alpha = \frac{1}{n}-1 \\
u*ctg \alpha = \frac{1-n}{n} \\u= \frac{1-n}{n*ctg\alpha} \\
[/tex]
Calcule:
[tex]u= \frac{1-0,6}{0,6*ctg30} =0,3849[/tex]
