Centripetal Force (2D)

Swing a ball on a string and it never travels toward or away from your hand — it moves in a circle because the string constantly pulls it inward, toward the centre. That inward pull is the centripetal force, F = mv²/r (equivalently F = mω²r for angular velocity ω), and it is the same force that keeps a satellite in orbit, a car gripping a curve, or a rider pinned to the wall of a spinning fairground ride. This 2D top-down companion lets you dial in the ball's mass, the radius of its circular path and its angular velocity, and watch the required centripetal force and speed update live alongside animated force and velocity vectors. Cut the string at any moment and the ball does not fly straight outward as intuition often suggests — with the inward force gone, Newton's first law takes over and the ball continues in a straight line along the tangent to the circle at the instant of release, exactly as the site's interactive 3D version of this demonstration shows.