Buat beserta jalannya

17.cara: a = F: m
                 =20 N : 2 Kg
                 = 10 m/s2

18. cara : a = (F- f ) : m
                   = ( 30 N- 6N ) : 4 Kg
                   = 24 N : 4 kg
                   = 6 m/s2