Rotational Motion Video Analysis

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     In the Mckayla Maroney video, the gymnast does a perfect vault. She runs, jumps, and turns while still accelerating. This action allows her to make a perfect jump and turns in the air while landing perfectly. However, momentum is still conserved through this process. Throughout the vault, linear motion as well as rotational motion is applied. Rotational motion consists of a body moving within an axis. In other words, there is a point that the rigid object is rotating or turning on. Referring back to the Mckayla Maroney video, the gymnast receives such a high score on her vault because she has a perfect RIGID body shape that is maintain throughout her experiment, and rigid body rotation is achieved. 



     Compared to the first video, the rotational movement of the diver is much more exaggerated making it easier to be seen. In both situations, the concept of rotational motion and inertia are seen. In his case, Dana Kane, the diver uses the force in pushing off the diving board creating oscillation – a toggling back and forth between two points. The potential energy that was in the diver is transferred into kinetic energy as he begins to bounce on the diving board. In the air, the diver, in this case, tucks his body creating the smallest radius possible. By doing so, he is able to do more somersaults in the air.  When he switches over to a straight position where he is bent only at the hips, his radius is also small allowing him to transition into his somersaults easily. Because he  has a smaller radius, he is closer to his center of mass. His torque, the tendency of a particular force to rotate around a certain axis, increases as he plunges toward the water. T=Fd. As his distance increases so does torque.

     The third video showed more deeply the root of rotational motion: the center of mass. The wine glass represented the center of mass. When an object is at its center of mass, net torque is neglected, and the object is in static equilibrium. As the wine glass hits the broom\stick, the broomstick instantly breaks and rotates. As shown in the video, both pieces of broomstick spin inward towards the point at which the broomstick was broken. The two pieces of the broomstick never touch each other, spinning on their axes. The pieces of broomstick spin inward because they were broken at their center of mass. The center of mass is also the center of rotation.