Korzystamy ze wzoru na energię kinetyczną:
[tex]E_{k} = \frac{1}{2}mv^{2}[/tex]
gdzie:
Ek - energia kinetyczna [J]
m - masa [kg]
v - prędkość ciała [m/s]
1.
[tex]dane:\\m = 80 \ kg\\v = 11\frac{m}{s}\\szukane:\\E_{k} = ?\\\\E_{k}= \frac{1}{2}mv^{2}\\\\E_{k} = \frac{1}{2}\cdot80 \ kg\cdot(11\frac{m}{s})^{2}\\\\E_{k} = 4 \ 840 \ J = 4,84 \ kJ\\\\(1 \ kJ = 1000 \ J)[/tex]
2.
[tex]dane:\\m = 1 \ 200 \ kg\\v = 108\frac{km}{h} = 108\cdot\frac{1000 \ m}{3600 \ s} = 30\frac{m}{s}\\szukane:\\E_{k} = ?\\\\E_{k} = \frac{1}{2}mv^{2}\\\\E_{k} = \frac{1}{2}\cdot1200 \ kg\cdot(30\frac{m}{s})^{2}\\\\E_{k} = 540 \ 000 \ J = 540 \ kJ[/tex]
3.
[tex]dane:\\m = 100 \ t = 100 \ 000 \ kg=10^{5} \ kg\\v = 10\frac{km}{s} = 10000\frac{m}{s}=10^{4} \ \frac{m}{s}\\szukane:\\E_{k}=?\\\\E_{k}=\frac{1}{2}mv^{2}\\\\E_{k} = \frac{1}{2}\cdot10^{5} \ kg\cdot(10^{4} \ \frac{m}{s})^{2}=\frac{1}{2}\cdot10^{13} \ J=\frac{1}{2}\cdot10\cdot10^{12} \ J\\\\E_{k} = 5\cdot10^{12} = 5 \ TJ \ (teradzuli)[/tex]
(1 TJ = 10¹² J)
