[tex]41.t=t_1+t_2d_1=d_2=d\\\\D=d_1+d_2=2d=>d=\frac{D}{2} \\t_1=\frac{d_1}{v_1}=\frac{d}{v_1}=\frac{D}{2v_1} \\ t_2=\frac{d_2}{v_2}=\frac{d}{v_2}=\frac{D}{2v_2}\\D=v_m*t=>v_m=\frac{D}{\frac{D}{2v_1}+\frac{D}{2v_2}}=\frac{D}{D(\frac{v_2+v_1}{2v_1v_2})}=\frac{2v_1v_2}{v_1+v_2}=\frac{2*60*40}{60+40}=\frac{4800}{100}=48 km/h=>v_m=48 km/h \\[/tex]
[tex]42.m=100 t=10^5 kg\\v=36 km/h=10 m/s\\\vec{F}+\vec{G}+\vec{N}+\vec{F_f}=m\vec{a}\\Ox:F-F_f=ma\\Oy:N-mg=0=>N=mg\\F_f=\mu N=\mu mg\\F-F_f=ma=>F=ma+\mu mg=10^5*0,9+0,01*10*10^5=10^5 N\\P=F*v=10^5*10=10^6 W=1MW=>P=1 MW[/tex]
