Đáp án:
\(\begin{array}{l}
a.{h_{\max }} = 7m\\
b.{v_{\max }} = 2\sqrt {35} m/s\\
c.h' = 1,75m
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
W = {W_{t\max }}\\
mgh + \frac{1}{2}m{v^2} = mg{h_{\max }}\\
10.2 + \frac{1}{2}{.10^2} = 10.{h_{\max }}\\
\Rightarrow {h_{\max }} = 7m\\
b.\\
{W_{t\max }} = {W_{d\max }}\\
mg{h_{\max }} = \frac{1}{2}mv_{\max }^2\\
10.7 = \frac{1}{2}v_{\max }^2\\
\Rightarrow {v_{\max }} = 2\sqrt {35} m/s\\
c.\\
{W_d}' = 3{W_t}'\\
\Rightarrow {W_t}' = \frac{W}{4} = \frac{{{W_{t\max }}}}{4}\\
mgh' = \frac{{mg{h_{\max }}}}{4}\\
\Rightarrow h' = \frac{{{h_{\max }}}}{4} = \frac{7}{4} = 1,75m
\end{array}\)
