[tex]\displaystyle\sf\\(ca~sa~urce~corpul~pe~plan~inclinat):\\\\pe~Ox:F=G_t=mgsin\alpha=15\cdot10\cdot sin30^{\circ}=75N,~pentru~ca~urca~\\cu~viteza~constanta,~F=f_f=75N.\\\\(ca~sa~ramana~in~repaus):\\\\fie~F'~forta~pentru~care~corpul~ramane~in~repaus.\\pe~Ox:F'-G_t-F_f=0 \implies F'=G_t+F_f=mgsin\alpha+\mu N=\\mgsin\alpha+\mu mgcos\alpha\approx 114N~(am~obtinut~pe~calculator~113,971..).\\\\(randamentul~planului~inclinat):\\\\[/tex]
[tex]\displaystyle\sf\\\eta =\frac{L_u}{L_c}=\frac{G_tl}{(G_t+f_f)l}=\frac{mgsin\alpha}{mgsin\alpha+\mu N}=\frac{mgsin\alpha}{mgsin\alpha+\mu mgcos\alpha}=\frac{sin\alpha}{sin\alpha+\mu cos\alpha}.\\asadar,~in~cazul~nostru~\eta\approx 0,6.[/tex]
