Najpierw zamiana jednostek
m = 20 t = 20 000 kg = 2*10^4 kg
v=900\frac{km}{h}=900*\frac{1000m}{\frac{1}{3600}s}=900000m*\frac{3600}{1s}=9*10^5*3,6*10^3=
32,4*10^8=3,24*10^9[\frac{m}{s}]
h = 3 km = 3000 = 3*10^3 m
E_p=mgh=2*10^4kg*10\frac{m}{s^2}*3*10^3m=6*10^8[\frac{kg*m^2}{s^2}]=6*10^8J
E_k=\frac{mv^2}{2}=\frac{2*10^4kg*(3,24*10^9{\frac{m}{s}})^2}{2}=\frac{2*10^4*10,5*10^{18}}{2}[\frac{kg*m^2}{s^2}]\approx10^{23}J
E_{mech}=E_P+E_k=
1 gigadżul 1GJ=10^9J
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