1.
t1=4km:(20km/h)=0,2h
t2=12km:(40km/h)=0,3h
t=0,2+0,3=0,5h
Vśr=16km:0,5h=32km/h
2.
s=t*v
t=s/v
t1=5/20=0,25h
t2=12/16=0,75h
t=t1+t2=0,75+0,75=1h
s=s1+s2
s=5+12=17km
v=s/t
v=17/1=17km/h
3.
s1=10 km
s2=14 km
s=s1+s2=10+14=24 km
v=s/t /*t
vt=s/:v
t=s/v
v1=5 km/h
t1=10 /5=2 h
v2=3,5 km/h
t2=14/3,5=4 h
t=t1+t2=2+4=6 h
v=24/6=4 km/h - prędkość średnia
