Odpowiedzi

2009-05-11T17:16:30+02:00
Vśr = s/t
s = 2s1
t = s1/v1+s1/v2 = s1/40+s1/60 = (3s1+2s1)/120 = 5s1/120 = s1/24
vśr = (2s1)/(s1/24) = 48 km/h