[tex]Dane:\\a = 0,43\frac{m}{s^{2}}\\s = 2,1 \ km = 2 \ 100 \ m\\v_{k} = 74\frac{km}{h} = 74\cdot\frac{1000 \ m}{3600 \ s} = 20,(5) \ \frac{m}{s} \approx 20,56\frac{m}{s}\\v_{p} = \frac{1}{2}v_{k} \approx \frac{1}{2}\cdot20,56\frac{m}{s} \approx 10,28\frac{m}{s}\\Szukane:\\t = ?\\s = ?[/tex]
Rozwiązanie
Czas:
[tex]v_{k} = v_{p}+at\\\\at = v_{k}-v_{p} \ \ /:a\\\\t = \frac{v_{k}-v_{p}}{a}\\\\t = \frac{(20,56-10,28)\frac{m}{s}}{0,43\frac{m}{s^{2}}}\\\\\boxed{t \approx23,9 \ s}[/tex]
Droga:
[tex]s = v_{p}\cdot t+\frac{1}{2}at^{2}\\\\s \approx 10,28\frac{m}{s}\cdot23,9 \ s + \frac{1}{2}\cdot0,43\frac{m}{s^{2}}\cdot(23,9 \ s)^{2}\\\\s \approx 245,69 \ m + 122,81 \ m\\\\\boxed{s\approx122,81 \ m}[/tex]
