Отметь как лучший)
1. 43 сек
2.~91
3.1200м/c
4.~7м
5.~0.1м
6.1м/c
7.2.5м
S=a*t²/2 ,
парабола функции S=t²/2 из начала координат
90=25 м/с
s=s1+s2=0.5s+0.5s<span>
t=t1+t2
t1=0.5s/v</span>₁<span>
t2=0.5s/v</span>₂<span>
vcp=s/t=s/(t1+t2)=s/(0.5s/v</span>₁<span>+0.5s/v</span>₂<span>) </span>Сократим на<span> s
vcp=1/(0.5/v</span>₁<span>+0.5/v</span>₂<span>)=2*v</span>₁<span>*v</span>₂<span>/(v</span>₁<span>+v</span>₂<span>)=2*25*15/(25+15)= 750/40=18.75 (</span>км/ч<span>)</span>