You are driving down the road at 35 mph. what is your speed in m/s?

15.64m/s

Explanation:

This is a unit of speed which is the rate of change of distance with time

I am driving at 35mph: and I want to express as m/s

  mph means miles per hour

This suggests that I have to convert miles to m and hrs to secs:

for distance                    1.609km = 1mi

                                        1000m = 1km

for time:

                 1hr = 60minutes

                 1min = 60seconds

Using dimensional analysis:

      x   x   x   x  

   = 15.64m/s