You don't want to hit someone. Fc means force circular - force excerted to keep the circular rotation going. Force of circular motion. Vt is velocity tangential. Velocity of whirling object you get when your spinning the stuff.
Delta t is change in time.
Hence, it would always be .75 m constantly. For trial 6, we slightly went below .75 m to maybe .74 m, but because it was only such a slight difference we stayed with .75 m because it was a small difference. However, my group was very bored. Because there was .75 m, and it already had been tested. We thought since we already had data for that, that we might as well put in .25 m for the fun, thinking maybe something else might show up if we do it by .25 m increments.