1.
[tex]dane:\\m = 3 \ kg\\v_{o} = 30\frac{km}{h} = 30\cdot\frac{1000 \ m}{3600 \ s} = 8,(3)\frac{m}{s} = 8,33\frac{m}{s}\\g = 10\frac{m}{s^{2}}\\szukane:\\H = ?\\\\E_{p} = E_{k}\\\\mgH = \frac{mv_{o}^{2}}{2} \ \ /:mg\\\\H = \frac{v_{o}^{2}}{2g}\\\\H = \frac{(8,33\frac{m}{s})^{2}}{2\cdot10\frac{m}{s^{2}}} = 3,47 \ m[/tex]
2.
[tex]dane:\\m = 400 \ kg\\h = 20 \ m\\s = 10 \ m\\g = 10\frac{m}{s^{2}}\\szukane:\\W = ?\\\\W = W_1 + W_2\\\\W_1 = E_{p} = m\cdot g\cdot h\\\\W_2 = F\cdot s = m\cdot g\cdot s\\\\W = mgh+mgs = mg(h+s)\\\\W = 400 \ kg\cdot10\frac{m}{s^{2}}\cdot(20 \ m+10 \ m)\\\\W = 120 \ 000 \ J = 120 \ kJ[/tex]
