The heavier the hanging mass was, the more force was required by the person swinging the device in order to raise it. This increase in force exerted on the device translated into an increase in Vt for the rubber stopper. In these the radius was increased, and subsequently, the tangential speed also increased. Again, the reason has to do with force. As the radius becomes longer, it becomes more difficult to swing.
More force is required on the part of the person swinging the device.
As the force exerted on the device increases, so does the tangential velocity. In order for the stopper to gain enough force to raise the hanging mass, it must move at a faster speed as teh length of the radius increases. In the final six trials, the mass of the rubber stopper was varied. In these trials, as the mass of the rubber stopper was increased, the tangential speed dropped. Th force generated by the whirling rubber stopper is what pulled the string up through the tubing, raising the hanging mass.