There are three types of Box2D bodies: static, dynamic, and kinematic.
A static body does not react to any force, impulse, or collision and does not move. A static body can only be moved manually by the user. By default, every Box2D body is a static body, and that's why the ball does not move. A static body also does not collide with other static or kinematic bodies.
A dynamic body reacts to forces, impulses, collisions, and any other world event. Dynamic bodies can also be moved manually, although I'd suggest to let them be moved by world forces, and collide with all body types.
A kinematic body is something hybrid between a static and a dynamic body. Kinematic bodies do not react to forces, ...
