Energia kinetyczna
[tex]E_k=\frac{mv^2}{2}[/tex]
1.
ma=80 kg
va=18 km/h
mb=8 g = 0,008 kg
vb=400 m/s
[tex]v_a=18\frac{km}{h}=18*\frac{1000 \ [m]}{3600 \ [s]}=5 \ \frac{m}{s}[/tex]
[tex]E_k_a=\frac{m_av^2_a}{2}=\frac{80 \ [kg]*(5 \ [\frac{m}{s}])^2}{2}=1000 \ J\\ \\E_k_b=\frac{m_bv^2_b}{2}=\frac{0,008 \ [kg]*(400 \ [\frac{m}{s}])^2}{2}=640 \ J\\ \\E_k_a > E_k_b[/tex]
2.
ma=18 t = 18 000 kg
va=500 m/s
mb=2 000 t = 2 000 000 kg
vb=20 m/s
[tex]E_k_a=\frac{m_av^2_a}{2}=\frac{18 \ 000 \ [kg]*(500 \ [\frac{m}{s}])^2}{2}=2 \ 250 \ 000 \ 000 \ J\\ \\E_k_b=\frac{m_bv^2_b}{2}=\frac{2 \ 000 \ 000 \ [kg]*(20 \ [\frac{m}{s}])^2}{2}=400 \ 000 \ 000 \ J\\ \\E_k_a > E_k_b[/tex]