<span>191)</span>
<span>Дано: </span>
<span>h = 20 м; S = 6 м.</span>
<span><span>Найти: t, v</span>0<span>.</span></span>
<span><span>Решение:</span></span>
1)h=gt^2/2
t=sqrt{2h/g}=sqrt{2*20/10}=2 c
2)Vo=S/t=s*sqrt{g/2h}=6*sqrt{10/2*20}=3 м/c
<span>Ответ: t = 2 с, v</span>0<span> = 3 м/с.</span>
<span>190)</span>
<span>l = V</span>x<span> t, где t - время падения (у = 0)</span>
<span>a)Voy=Vo*sin\alpha=0</span>
t=sqrt{2h/g}=sqrt{2*20/9.8}=2c
l=Vocos\alpha*t=Vot=25*2=50v
б)Vx=Vocos\alpha=25*sqrt{3}/2=21.6м/c
Voy=Vosin\alpha=25*1/2=12.5м/с
y=yo+Voy-gt^2/2=20+12.5t-9.8t^2/2
<span>при падении у = 0, t</span>1<span> = 36с, t ≥ 0, следовательно,</span>
<span>t2=-1.1c</span>
t=3.6c
l=Vxt=21.6*3.6=78м
в)Vx=Vocos\alpha=25*sqrt{3}/2=21.6м/c
Vy=Vosin\alpha=25*(-1/2)=-12.5m/c
y=yo+Voyt-gt^2/2=20-12.5-9.8t^2/2
<span>у = 0, t</span>1<span> = 1,1с, но t ≥ 0, следовательно, t</span>2<span> = -3,5с</span>
<span><span>t = 1,1c</span></span>
l=Vxt=21.6*1.1=24м