Mathcad-sheets and animations of the Study 8 of the book
2^5 Problems for STEM Education
Live kinematic schemes
Arm of Hella
 Hella is a fictional character from the novel The Master and Margarita by the Russian writer Mikhail Bulgakov. The novel was written between 1928 and 1940, but unpublished in book form until 1967. Hella is a beautiful, redheaded succubus. She serves as maid to Woland and his retinue. Described as being "perfect, were it not for a purple scar on her neck" — the scar suggesting that she is also a vampiress. Reference to her arm will be clear later in the study.