1.
[tex]Dane:\\v_1} = 50\frac{km}{h}\\t = 20 \ s\\v_2 = 100\frac{km}{h}\\Szukane:\\a = ?\\\\Rozwiazanie\\\\a = \frac{\Delta v}{t}\\\\\Delta v = v_2-v_1 = 100\frac{km}{h} - 50\frac{km}{h} = 50\frac{km}{h} = 50:3,6 \ \frac{m}{s}=13,(8) \ \frac{m}{s}\approx13,9\frac{m}{s}\\\\a \approx \frac{13,9\frac{m}{s}}{20 \ s}\\\\\boxed{a \approx 0,7\frac{m}{s^{2}}}[/tex]
2.
[tex]Dane:\\v_{o} = 0\\t = 7 \ s\\a = 10\frac{m}{s^{2}}\\Szukane:\\v = ?\\\\Rozwiazanie\\\\v = a\cdot t\\\\v = 10\frac{m}{s^{2}}\cdot7 \ s\\\\\boxed{v = 70\frac{m}{s}}[/tex]
3.
[tex]Dane:\\v_{o} = 0\\t = 20 \ s\\s = 200 \ m\\Szukane:\\v = ?\\\\Rozwiazanie\\\\s = \frac{1}{2}at^{2}\\\\ale\\\\a = \frac{v}{t}\\\\s = \frac{1}{2}\cdot\frac{v}{t}\cdot t^{2}\\\\s = \frac{1}{2}v\cdot t \ \ \ |\cdot2\\\\v\cdot t = 2s \ \ \ /:t\\\\v = \frac{2s}{t}\\\\v = \frac{2\cdot200 \ m}{20 \ s}\\\\\boxed{v = 20\frac{m}{s}}[/tex]
