Question

Ma puteti ajuta va rog frumos?

Answer 1

$L_1=mgh=50*10*4=2000 J=2 kJ\\sin\alpha=\frac{h}{l}=\frac{4}{8}=0,5\\F-G_t-F_f=0=>F=F_f+G_t=F_f+mgsin\alpha=10+50*10*0,5=10+250=260 N\\L_2=F*l=260*8=2080 N\\\eta=\frac{Gh}{Fl}=\frac{mgh}{Fl}=\frac{50*10*4}{260*8}=\frac{2000}{2080}=0,96=96\%$