18.
Z wykresu odczytujemy:
a = 4 m/s²
F = 3 N
m = ?
[tex]F = m\cdot a \ \ |:a\\\\m = \frac{F}{a}\\\\m = \frac{3 \ N}{4\frac{m}{s^{2}}} = \frac{3 \ kg\cdot \frac{m}{s^{2}}}{4\frac{m}{s^{2}}}\\\\\boxed{m = 0,75 \ kg}[/tex]
19.
m = 1 kg
v₀ = 0 m/s
t = 2 s
v = 0,6 m/s
F = ?
[tex]F = m\cdot a\\\\ale\\\\a = \frac{\Delta v}{t} = \frac{v-v_{o}}{t} = \frac{v}{t} = \frac{0,6\frac{m}{s}}{2 \ s} = 0,3\frac{m}{s^{2}}\\\\F = 1 \ kg\cdot0,3\frac{m}{s^{2}}\\\\\boxed{F = 0,3 \ N}[/tex]
