\[h = v_{o}t - 4,9t^{2};\]
\[v_{0} = 360\ м\text{/}с;\]
\[t = 10\ с.\]
\[h^{'}(t) = v_{0} - 4,9 \bullet 2t = 360 - 9,8t;\]
\[h^{'}(10) = 360 - 9,8 \bullet 10 =\]
\[= 360 - 98 = 262;\]
\[3)\ Скорость = 0:\]
\[360 - 9,8t = 0\]
\[9,8t = 360\]
\[t \approx 37.\]
\[Ответ:\ \ v = 262\ м\text{/}с;\ t \approx 37\ с.\]