[JohnHorton]

In response to my previous post, I figured out the initial launch velocity needed.
Assuming:
-Kinetic minibots are allowed
-4N triggers the switch (as indicated in GM 2.2.5)
-A section of PVC around the tower with some hinging and latching weighs in at 120g
-The target switch takes 1 cm to trigger
-Friction turns off for the day
The initial launch velocity would need to be 7.5 m/s.

I rounded up gravity to 10 m/s^2 and rounded up most of my numbers to two sig. figures.

This is on the outside for that weight of PVC. I think +/- .5m/s would be fine, depending on friction.