Dane: E mechaniczna= 0,8 KJ v= 72 km/h h= 20m   Oblicz: masę (m)

E mech = 0,8 KJ= 0,8*1000 =800 J v-72 km/h=20m/s g=9,81   E mech= E pot+ E kin Emech= m*g*h+ [latex]frac{mv^{2}}{2}[/latex] E mech= m* [latex](g*h+frac{v^{2}}{2})[/latex] m= [latex]frac{E mech}{(g*h+frac{v^{2}}{2})}[/latex] m=800/(9,81*20)+[latex]20^{2}[/latex]/2 m=800/196,2+200 m=800/396,2 m=2,02kg