Question

What helps in writing with a pen or pencil on a paper?
A) Magnetic force
B) Electric charge
C) Chemical force
D) Frictional force

Answer 1

Hint:The pen or pencil and paper are macroscopic objects which are unreactive to each other. They also are not electrically charged.

Complete step-by-step solution:
Frictional force helps us in writing with a pen or pencil on a paper. The surface of paper, even though it looks smooth from the naked eye, is very irregular on the microscopic level. These irregularities cause the friction of the paper to get higher. When we write with a pencil, this friction causes the lead particles to be rubbed off from the nib of the pencil and get stuck on the paper so we can see what we are writing or drawing. When we write with a pen, this friction causes the ink particles to stay on the paper and dry off. In the absence of friction or in the cases of low friction, like glass slabs, we cannot write with a pencil or a normal pen. To write on such a smooth surface with low friction, we need markers or other types of pens.

There are no magnetic forces, chemical forces or electrical charges present to contribute to the process of writing. The forces on the atomic level are too small to act in these types of cases. The pen and paper are also generally chemically non-reactive to each other so there is no presence of chemical process.

Note: Friction has many other applications as well. It helps us walk and sit or stand at one place. Friction also holds the nails in their place when hammered into a wall. Friction is undesirable in places like machines, but it is also useful in some places like in applying brakes.