P = m*g / S
p = 48*10 / (320*10⁻⁴) = 15 000 Н или 15 кН
2,3 МДж = 2,3 * 10^6 Дж = 2300000 Дж
Ответ:
Объяснение:
72 умножаем на одну третью часа= 24 километра
Запишем закон движения и изменения скорости тела
![x(t)= v_0\cos\alpha t\\ y(t)= v_0\sin\alpha t-gt^2/2\\ v_y(t) = v_0\sin\alpha-gt](https://tex.z-dn.net/?f=x%28t%29%3D+v_0%5Ccos%5Calpha+t%5C%5C%0Ay%28t%29%3D+v_0%5Csin%5Calpha+t-gt%5E2%2F2%5C%5C%0Av_y%28t%29+%3D+v_0%5Csin%5Calpha-gt)
В наивысшей точке подъема vy=0 отсюда
![v_y(\tau) = 0\\ v_0\sin\alpha - g\tau = 0\\ \tau = v_0\sin\alpha/g \\ H = y(\tau) = \frac{v_0^2\sin^2\alpha}{2g}](https://tex.z-dn.net/?f=v_y%28%5Ctau%29+%3D+0%5C%5C%0Av_0%5Csin%5Calpha+-+g%5Ctau+%3D+0%5C%5C%0A%5Ctau+%3D+v_0%5Csin%5Calpha%2Fg+%5C%5C%0AH+%3D+y%28%5Ctau%29+%3D+%5Cfrac%7Bv_0%5E2%5Csin%5E2%5Calpha%7D%7B2g%7D)
Когда тело упадет на землю y =0 отсюда
![y(\tau_2) = 0\\ v_0\sin\alpha\tau_2-g\tau_2^2/2 = 0\\ \tau_2 = 2v_0\sin\alpha/g\\ L = x(\tau_2) = \frac{2v_0^2}{g}\sin\alpha\cos\alpha](https://tex.z-dn.net/?f=y%28%5Ctau_2%29+%3D+0%5C%5C%0Av_0%5Csin%5Calpha%5Ctau_2-g%5Ctau_2%5E2%2F2+%3D+0%5C%5C%0A%5Ctau_2+%3D+2v_0%5Csin%5Calpha%2Fg%5C%5C%0AL+%3D+x%28%5Ctau_2%29+%3D+%5Cfrac%7B2v_0%5E2%7D%7Bg%7D%5Csin%5Calpha%5Ccos%5Calpha)
Максимальная высота и длина такие
![H = \frac{v_0^2\sin^2\alpha}{2g}\\\\ L = \frac{2v_0^2}{g}\sin\alpha\cos\alpha](https://tex.z-dn.net/?f=H+%3D+%5Cfrac%7Bv_0%5E2%5Csin%5E2%5Calpha%7D%7B2g%7D%5C%5C%5C%5C%0AL+%3D+%5Cfrac%7B2v_0%5E2%7D%7Bg%7D%5Csin%5Calpha%5Ccos%5Calpha)
Отсюда
![\frac{4\sin\alpha\cos\alpha}{\sin^2\alpha} = 4\\\\ \cot\alpha = 1\\\\ \alpha = 45^\circ](https://tex.z-dn.net/?f=%5Cfrac%7B4%5Csin%5Calpha%5Ccos%5Calpha%7D%7B%5Csin%5E2%5Calpha%7D+%3D+4%5C%5C%5C%5C%0A%5Ccot%5Calpha+%3D+1%5C%5C%5C%5C%0A%5Calpha+%3D+45%5E%5Ccirc)