Let's say you two objects with weight of 2 kilograms but one is narrower and one wider. They are said to be similar coefficient of friction against a surface.. but what if the surface is rough? Won't the wider object has more friction? Or still the same? If still the same.. what if the surfaces of the wider object has more roughness compared to the surface of the narrower surface.. then it is no longer similar? And we can say the coefficient of friction of the rougher surface is more in value?