[tex]\displaystyle\bf\\Se da:\\m=5~tone\\V=30~Km/h\\\\Folosim~formula:\\\\Ec=m\cdot\frac{V^2}{2}\\\\unde:\\E~(energia)~se~masoara~in~Jouli~(J)~~De~la~fizicianul~Joule.\\m~(masa)~se~masoara~in~Kg\\\\V~(Viteza)~se~masoara~in~m/s\\\\Rezolvare:\\\\Pasul~1:~Transformam~unitatile~de~masura:\\\\m=5~tone=5000~Kg\\\\V=30~\frac{Km}{h}=30\times\frac{1000~m}{3600~s}=30:3,6=8,\!(3)~m/s\approx~8,\!33~m/s[/tex]
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[tex]\displaystyle\bf\\Pasul~2:~Calculam~energia~cinetica.\\\\Ec=m\frac{V^2}{2}=\frac{mV^2}{2}=\frac{5000\times8,\!33^2}{2}=\\\\=\frac{5000\times4668,\!98}{2}\approx\frac{5000\times4669}{2}=\\\\=2500\times4669=11672500~J\approx\boxed{\bf11,\!673~MJ~~(Mega~Jouli)}[/tex]
