Đáp án:
\(\begin{array}{l}
a.\\
h = 5m\\
b.\\
v = 8,165m/s
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
W = \frac{1}{2}m{v^2} = mgh\\
h = \frac{{{v^2}}}{{2g}} = \frac{{{{10}^2}}}{{2.10}} = 5m\\
b.\\
W = {W_d} + {W_t} = {W_d} + 0,5{W_d} = 1,5{W_d}\\
mgh = 1,5.\frac{1}{2}mv{'^2}\\
v = \sqrt {\frac{{2gh}}{{1,5}}} = \sqrt {\frac{{2.10.5}}{{1,5}}} = 8,165m/s
\end{array}\)