Question

The tip of a drawing pin has an area of $0.01m{m^2}$. Find the pressure exerted by it if a force of 20N is applied by it.

Answer 1

Hint: To find the solution of these kinds of questions write down all the given physical quantities, convert the units in the standard form and then apply the formula of pressure to find the required solution.
Formula Used: Pressure $ = \dfrac{{Force}}{{Area}}$

Complete answer:
It is given that the tip of the drawing pin has an area of $0.01m{m^2}$.
Converting the unit into standard form we get,
Area $ = 0.01m{m^2} = \dfrac{{0.01}}{{1000 \times 1000}}{m^2} = \dfrac{1}{{100000000}}{m^2}$
According to the given question,
Force applied by the drawing pin is,
Force $ = 20N$
Pressure is explained as the force which is applied perpendicular to the surface of an object per unit area over which that force is distributed. In other words, when a force of ‘F’ Newton is applied perpendicularly to a surface of area ‘A’, then the pressure exerted on the surface by the force is equal to the ratio of ‘F’ to ‘A’. The SI unit of pressure is expressed in Pascal (Pa). One pascal is defined as the force of one newton applied over a surface area of a one-meter square.
Mathematically it is given as,
Pressure $ = \dfrac{{Force}}{{Area}}$
Pressure $ = \dfrac{{20}}{{\left( {\dfrac{1}{{100000000}}} \right)}} = 2000000000$pascal
$\therefore {\text{Pressure}} = 2 \times {10^9}Pa$
Hence, the pressure exerted by the drawing pin is $2 \times {10^9}Pa$.

Note:
Students tend to make mistakes by solving the question without converting the units in the standard form. They need to be careful while solving these kinds of questions.
Since the pressure is dependent on the area of the body over which the force is acting, then the pressure can be increased and decreased without any change in the force.