Areal velocity equal to the magnitude of the cross product of vectors "AB" and "AC". This area can also be viewed as a vector with this magnitude, pointing in a direction perpendicular to the parallelogram; this vector is the cross product itself: Hence The areal velocity is this vector area divided by Δ"t" in the limit that Δ"t" becomes vanishingly small: But, formula_4 is the velocity vector formula_5 of the moving particle, so that On the other hand, the angular momentum of the particle is and hence the angular momentum equals 2"m" times the areal velocity. Conservation of areal velocity is a
C. N. Yang Institute for Theoretical Physics C. N. Yang Institute for Theoretical Physics The C. N. Yang Institute of Theoretical Physics (YITP) is a research center at Stony Brook University. In 1965, it was the vision of then University President J.S. Toll and Physics Department chair T.A. Pond to create an institute for theoretical physics and invite the famous physicist Chen Ning Yang from Institute for Advanced Study to serve as its director with the Albert Einstein Professorship of Physics. While the center is often referred to as "YITP", this can be confusing as YITP also stands for the Yukawa Institute for Theoretical Physics in Japan.