v0 = 54 km/h = 54* 1000 m/3600s =15 m/s v= 0 m/s delta_t = 30 min = 1800 s delta_v = 0 - 15 m/s = -15 m/s a = -15m/s /1800 s =( -1/120) m/s2 A do obliczeń wezmę przyspieszenie a bez minusa ===================== F = 700 N F = m*a /:a F/a = m m = F/a = 700 N / (1/120 m/s2) = 700 * 120 kg = 84000 kg Odp Masa auta wynosiła 84000 kg Myślę, że dobrze :-)
dane: F = 700 N = 700 kg*m/s2 v = 54 km/h = 54 x 1000m/3600s = 15 m/s t = 30 min = 30 x 60s = 1800 s szukane; m = ? Z II zasady dynamiki: F = m x a /:a m = F/a ale a = v/t = 15m/s /1800s = 1/120m/s2 m = 700kg*m/s2 /1/120m/s2 = 84000 kg m = 84 t ========= Odp.Szukana masa auta wynosi 84 t.
