Samochod przejechal 1/4 drogi w predkosci 40km/h,reszte drogi przejechal z predkoscia 80km/h. oblicz srednia predkosc

3x80km/h= 240km/h 240km/h+40km/h=280km/h 280km/h:4=70km/h

S1 = S/4 km v1 = 40 km/h S2 = ( 3/4 ) * S km v2 = 80 km/h t1 = S1 / v1 = ( S/4 ) km : 40 km/h = S/160 h t2 = S2 / v2 = (3/4)*S km : 80 km/ h = ( 3 /320)*S  h v śr = S/ t = S : ( t1 + t2 ) = S km : [ S/ 160 +  ( 3/320 ) * S ] h = = 1 km :  [ 1/160 + ( 3/320 ) ] h = 1 km : 2/320 + 3/320  h = = 1 km :  5/320 h = 1 * ( 320 / 5 )  km/h = 64 km/h Proszę ;**