Physics Uncovered on Instagram: "In an MIT physics lecture on free fall and weightlessness, Professor Walter Lewin demonstrated the idea in a striking and unforgettable way. He began by holding a stone and explaining that while standing still, his hand applied an upward normal force equal to the stone’s weight (mg), keeping it at rest. Then, to show what changes in free fall, he jumped off a table while still holding the stone. During the fall, both he and the stone accelerated downward together