Kinematic Spur gear

Visual Physics: Rolling Wheel Velocity DemonstratorThis educational model is a mechanical "proof" of a fascinating physics concept: In a rolling wheel, the top point moves twice as fast as the center (axle). While it sounds like a paradox, this hands-on tool uses a dual-rack system and a built-in ruler to make the math undeniable and easy to visualize for students and makers alike.How it WorksThe model features a central wheel geared to a fixed bottom track and a sliding top track.The Scale: The integrated ruler allows you to track the exact displacement of the axle.The Top Bar: As you move the wheel, you will notice that the top bar travels exactly double the distance of the wheel's center in the same amount of time.The Science (Kinematics)For a wheel rolling without slipping:The Bottom Point (contact with the ground) has an instantaneous velocity of $0$.The Center Point moves at velocity $v$.The Top Point moves at velocity $2v$ because its speed is the sum of the forward