1.
[tex]Dane:\\v_{o} = 0\\t = 7 \ s\\v = 6\frac{m}{s}\\Szukane:\\s = ?\\\\\\s = \frac{1}{2}at^{2}\\\\a = \frac{v}{t}\\\\s = \frac{1}{2}\cdot\frac{v}{t}\cdot t^{2}\\\\s = \frac{1}{2}vt\\\\s = \frac{1}{2}\cdot6\frac{m}{s}\cdot 7 \ s\\\\\boxed{s = 21 \ m}[/tex]
2.
[tex]Dane:\\v_{o} = 0\\a = 1,5\frac{m}{s^{2}}\\v = 9\frac{m}{s}\\Szukane:\\t = ?\\\\\\v = a\cdot t \ \ /:a\\\\t = \frac{v}{a}\\\\t = \frac{9\frac{m}{s}}{1,5\frac{m}{s^{2}}}\\\\\boxed{t = 6 \ s}[/tex]