18.
[tex]dane:\\m = 5 \ kg\\a = 1\frac{m}{s^{2}}\\szukane:\\F_{w} = ?\\\\F_{w} = m\cdot a\\\\F_{w} = 5 \ kg\cdot1\frac{m}{s^{2}}\\\\F_{w} = 5 \ N\\\\Odp. \ C.[/tex]
19.
[tex]dane:\\m = 5 \ kg\\F_1 = 50 \ N\\F_2 = 10 \ N\\F_2 = 15 \ N\\F_3 = 20 \ N\\szukane:\\a = ?\\\\F_{w} = F_1 - (F_2 + F_3 + F_4)\\\\F_{w} = 50 \ N - (10 \ N + 15 \ N + 20 \ N) = 50 \ N - 45 \ N = 5 \ N\\\\a = \frac{F_{w}}{m}\\\\a = \frac{5 \ N}{5 \ kg}\\\\a = 1\frac{m}{s^{2}}[/tex]
