Water beads up on a waxed car but spreads on bare paint because of the balance between:

1. Whether a drop spreads depends on two competing attractions. 2. Attractive forces between molecules of the same type are called cohesive forces. 3. Attractive forces between molecules of different types are called adhesive forces. 4. On wax, cohesion within the water wins and the drop beads up. 5. On bare paint, adhesion to the surface wins and the water spreads. _Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 11 'Fluid Statics', sections 11.1-11.9_