I am a high school student and I was studying kinematics about position of a body. So, one thing I do not understand in this diagram is the position of woman. Initally, at $t=0$, this woman was at $x=1.5\,\text{m}$ from reference frame; but her hands, her legs or any point of the woman are at different positions. So how we can say that this woman is at $x=1.5\,\text{m}$? How we can define the position of the woman?