Đáp án:
\(\begin{array}{l}
a.\\
h' = 240m\\
b.\\
h = 60m\\
c.\\
v = 69,282m/s\\
d.\\
{F_c} = 360000N
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
\frac{1}{2}m{v^2} + mgh = mgh'\\
\frac{1}{2}{.20^2} + 10.4 = 10.h'\\
h' = 240m\\
b.\\
mgh' = \frac{1}{2}mv{'^2} + mgh\\
gh' = 4gh\\
h = \frac{1}{4}h' = \frac{1}{4}.240 = 60m\\
c.\\
mgh' = \frac{1}{2}mv{^2}\\
10.240 = \frac{1}{2}v{^2}\\
v = 69,282m/s\\
d.\\
a = \frac{{v{'^2} - v{^2}}}{{2s}} = \frac{{ - 69,{{282}^2}}}{{2.0,04}} = - 60000m/{s^2}\\
{F_c} = - ma = - 6.60000 = 360000N
\end{array}\)
