Se da:
a=0,8
n=75%=0,75
u=?
Formule:
n=Lu/Lc
n=mgh/Fd; h/d putem scrie ca sina
n=(mg/F)*sina
F=Ffr+Gn
F=uN+G*sina
F=umg*cosa+mg*sina
[tex]F= \frac{mg}{n}*sina\\
u*mg*cosa+mg*sina= \frac{mg}{n} *sina\\
u*cosa+sina= \frac{sina}{n} \\
u*cosa= \frac{sina}{n} -sina\\
u= \frac{ \frac{sina}{n}-sina }{cosa} \\
Calcule:\\
u= \frac{ \frac{sin0,8}{0,75}-sin0,8 }{cos0,8} =0,00465[/tex]