1.
[tex]dane:\\m = 3 \ kg\\v_{o} = 30\frac{km}{h} = 30:3,6\frac{m}{s} = 8,33\frac{m}{s}\\g = 10\frac{m}{s^{2}}\\szukane:\\H = ?\\\\Rozwiazanie\\\\E_{p} = E_{k}\\\\mgH = \frac{mv_{o}^{2}}{2g} \ \ /: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]
Odp. Ciało wzniesie się na wysokosć 3,47 m.
2.
[tex]dane:\\m = 400 \ kg\\h = 20 \ m\\s = 10 \ m\\g = 10\frac{m}{s^{2}}\\szukane:\\W = ?\\\\Rozwiazanie\\\\W = W_1 + W_2\\\\W_1 = E_{p} = mgh\\\\W_1 = 400 \ kg\cdot10\frac{m}{s^{2}}\cdot20 \ m = 80 \ 000 \ J = 80 \ kJ\\\\W_2 = F\cdot s \\F = m\cdot g\\\\W_2 = mgs\\\\W_2 = 400 \ kg\cdot10\frac{m}{s^{2}}\cdot10 \ m = 40 \ 000 \ J = 40 \ kJ\\\\W = 80 \ kJ + 40 \ kJ = 120 \ kJ[/tex]
Odp. Wykonana praca ma wartość 120 J.
