The comparative form of smooth is smoother, not more smooth.
smoothestThe superlative of 'smooth' is ' smoothest'.
smoother
smoother,smoothest.
smoother
Both are correct grammatically in English. It is because smooth, smoother and smoothest are the three forms.
smoother is comparative of word smooth.
smoother
smoother, smoothest
by cleaning the surface
Friction is the force that will decrease if the surface of the ramp is made smoother. Smooth surfaces reduce friction by allowing objects to slide more easily with less resistance.
Because friction is less on smooth surfaces. Smoother the surfaces, lesser the friction.