unit for distance = meter(m)
unit for time = second (s) or hour(hr)
unit for speed/ velocity= m/s or km/hr
distance = m/s * s (think of the 's' is cancel out)
km / hr * hr ('hr' cancel out)
3600s = 1 hrs
1000m = 1km
example:
50km/hr = 50 km /hr * 1000m/1km * 3600s/1hr = __ m/s
('km' got cancel and 'hr' got cancel, u left with 'm' and 's')
speed/ velocity = distance (m)/time (s)= m/s ( it always distance/ time)
time = m/ (m/s) ( 'm' cancel out and 's' goes to the top)