Where is the best place to strum a ukulele for maximum volume, and why?
From experience, maximum volume (and a good sound) seems to be achieved by strumming at the place where the neck and body of the uke meet, not the sound hole. I thought it had something to do with a lot of wood being there, and strumming at that spot somehow facilitating increased take-up of string vibration. A little bit of research and common sense later, I have an explanation which might better withstand rigorous scientific testing.
String vibrations are transferred to the body of the uke via the bridge and so it stands to reason that approximately half way between the nut and the saddle is the best place to get the most vibration from short ukulele strings as it encounters the least amount of resistance from the fixed points.
Have a look at your uke and you will probably find that where the neck meets the body is almost halfway between the nut and the saddle. A lot of chords are played in the first three frets which moves the halfway mark very close to the neck/body conjunction.
If you are playing chords a long way up the neck, moving your strumming hand to the relative halfway will help maintain the volume.