[tex]dane:\\v = 45\frac{km}{h} = 45\cdot\frac{1000 \ m}{3600 \ s} = 12,5\frac{m}{s}\\s = 1 \ km = 1000 \ m\\szukane:\\t = ?\\\\Rozwiazanie\\\\s = v\cdot t \ \ /:v\\\\t = \frac{s}{v}\\\\t = \frac{1000 \ m}{12,5\frac{m}{s}}\\\\t = 80 \ s = 1 \ min \ i \ 20 \ s[/tex]
Odp. Szukany czas to 80 s.