Đáp án:
\(\begin{array}{l}
a.\\
v' = 6,364m/s\\
b.\\
a = 2,46875m/{s^2}
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
{W_d}' - {W_d} = {A_P}\\
\frac{1}{2}mv{'^2} - \frac{1}{2}m{v^2} = Ph = 10mh\\
\frac{1}{2}.v{'^2} - \frac{1}{2}{1^2} = 10.4\\
v' = 6,364m/s\\
b.\\
s = \frac{h}{{\sin 30}} = \frac{4}{{\sin 30}} = 8m\\
a = \frac{{v{'^2} - {v^2}}}{{2s}} = \frac{{6,{{364}^2} - {1^2}}}{{2.8}} = 2,46875m/{s^2}
\end{array}\)