Đáp án:
\(y = g\frac{{{t^2}}}{2} = \frac{{g{x^2}}}{{2{v_0}^2}} = \frac{{{x^2}}}{{45}}\)
L=60m
v=25m/s
Giải thích các bước giải:
\(\begin{array}{l}
y = g\frac{{{t^2}}}{2} = \frac{{g{x^2}}}{{2{v_0}^2}} = \frac{{{x^2}}}{{45}}\\
L = {v_0}\sqrt {\frac{{2h}}{9}} = 15\sqrt {\frac{{2.80}}{{10}}} = 60m\\
v = \sqrt {{v_x}^2 + {v_y}^2} = \sqrt {{v_0}^2 + {{(gt)}^2}} = \sqrt {{v_0}^2 + {{(g\sqrt {\frac{{2h'}}{g}} )}^2}} = \sqrt {{{15}^2} + {{(10\sqrt {\frac{{2(80 - 60)}}{{10}}} )}^2}} = 25m/s
\end{array}\)