In sports, it is very common to see athletes performing jumps, where they impose rotations to their own bodies' elements and intentionally change their moment of inertia around the centre of mass (CM). When this occurs, weird effects are observed in the body's trajectories. In this work we study a jump called "Grand Jeté" of a ballerina, in which she moves her arms and legs to give the feeling that her body remains "floating" in the air for a long time. We use a computational model to calculate the position of the ballerina's CM during the jump and to explain quantitatively her motion in terms of a displacement of the CM in the ballerina's frame of reference, which enriches the study of the "Grand Jeté."