Đáp án:
\(\begin{array}{l}
1.\\
h = 5m\\
2.\\
a.\\
h = 15m\\
b.\\
v = 10\sqrt 3 m/s
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
1.\\
\frac{1}{2}m{v^2} = mgh\\
h = \frac{{{v^2}}}{{2g}} = \frac{{{{10}^2}}}{{2.10}} = 5m
\end{array}\)
2.
\(\begin{array}{l}
{W_t} = mgh\\
h = \frac{{{W_t}}}{{mg}} = \frac{{600}}{{4.10}} = 15m\\
b.\\
{W_t} = {W_d} = \frac{1}{2}m{v^2}\\
v = \sqrt {\frac{{2{W_t}}}{m}} = \sqrt {\frac{{2.600}}{4}} = 10\sqrt 3 m/s
\end{array}\)