For trials 9-14 change the radius for every 2 trials. For trials 15-20 change the stopper for every 2 trails. Record all data. Vt is tangential speed. Fc is mass times gravity.
Ms is mass of stopper.
For trials 1-8 the tangential speed Vs. Fc, the end result was that as the force that maintains circular motion increased tangential speed also increased. The radius and the mass of the stopper remained constant while the weight changes. As more more weight is added, the more force is needed to keep the whirling object in motion. Gravity is pushing the weight down.