If a car increases its velocity from 1m/s to 3.6km/hr in 5 seconds what's its acceleration

applying 1st eq of motion vf=vi+at here we have to find a=vf-vi/t, a = 1-1/5, a=0/5 then we got a=0 here (vf value 3.6km/h is converted in standard unit 3.6*1000/3600 so we get vf=1m/s²