Question

Un automobil parcurge 40℅ dintr o distanta cu viteza "v" si restul cu viteza constanta "nv" . Sa se calculeze viteza medie . Aplicatie numerica : v=40km/h si n= 1,5 . Multumesc anticipat !

Answer 1

d₁=40%d=40d/100=2d/5

d₂=d-d₁=d-2d/5=3d/5

t=t₁+t₂

d=d₁+d₂

v₁=40 km/h

v₂=nv₁=1,5*40=60 km/h

t₁=d₁/v₁=2d/5/v₁=2d/5v₁

t₂=d₂/v₂=3d/5/v₂=3d/5v₂

vm=d/t=d/(2d/5v₁+3d/5v₂)=1/(2v₂+3v₁)/5v₁v₂=5v₁v₂/(2v₂+3v₁)=5*40*60/(2*40+3*60)=12000/(80+180)=12000/260=46,15  km/h