Question

We have two identical metal sheets. One of them is rubbed with sandpaper and the other with ordinary paper. The one rubbed with sandpaper shines more than the other. Give reason.

Answer 1

Frictional force:

1. Frictional force is the force generated between two surfaces that are sliding against each other.
2. Friction is generated due to irregularity on the two surfaces that are in contact with each other.
3. When one object is rubbed over the other object, the irregularities on the surface gets entangled and causes friction.
4. The more the irregularities and the roughness, the more significant will be the friction.

Rubbed with sandpaper:

1. When metal sheet rubbed with sandpaper, more friction is created between the layers of the metal sheet and sandpaper.
2. It exerts more force on the dust particles, which are easily removed and thus reflects better shining.

Rubbed with ordinary paper:

1. When metal sheet rubbed with ordinary paper, less friction is created between the layers of the metal sheet and paper.
2. In this case frictional force is insufficient to remove dust particles, therefore it will shine less as compared to sandpaper.

Hence, the metal sheet rubbed with sandpaper will shine better as compared to ordinary paper.