vfinal=0=vinitial-at
t=vinitial;/a
t=70km/h :1m/s²=70/3,6 (m/s):1 m/s²=19,(4)s≈19,44s
as simple as that!!
(la impartire am folosit calculatortrul..::)
'capcana' consta in transformarea unitatiide masura a vitezei , in SI
1km/h=1000m/3600s=(1/3,6)* (m/s)