Odpowiedź :
Odpowiedź:
Wyjaśnienie:
s1 = 20 km
v1 = 40 km/h
s2= 20 km
v2= 60 km/h
t=?
vśr = ?
v=s/t
t=s/v
t1 = s1/v1 =20/40= 0,5 h=1/2h
t2= s2/v2= 20/60= 1/3h
t = t1+ t2
t = 1/2h + 1/3 h =5/6 h x60 = 50 min
Vśr = (20+20)/(5/6) =40/5/6 = 40 x 6/5 = 48 km/h