F śr = m*a a= (vk-- vp)/t F śr = m* (vk-- vp)/t vk= 60km/h = 60000m/3600s= 16.67 m/s vp = 40km/h= 40000m/3600s = 11,11 m/s F śr = 900km (16,67m/s - 11,11m/s)/4s = 1251 kg*m/s² = 1251 N
Jaka srednia siła działa na samochod o masie m=900kg, ktory w ciagu 4 sekund przyspiesza od predkości 40km/hdo 60 km/h 60km/h-40km/h=20km/h 20km/h=5i5/9m/s 5 i 5/9 m/s : 4s = 1 i 7/18 m/s kwadrat a=F/m 1 i 7/18 m/s kwadrat = F/900kg F=2500N
m = 900kg Δt = 4s = 1/900h Δv = 60 - 40 = 20km/h F = ma a = Δv/Δt F = m*Δv/Δt F = 900kg * 20km/h / 1/900h = 16200000 N
