Question

Identify which of the following show the applications of pressure in our everyday life?
(this question has multiple correct options)
A. The blade of ice-skating show is very sharp
B. It is easier to drive a sharp tipped nail into wood
C. Sharp knife cuts better
D. Foundation of high-building are kept wide

Answer 1

Hint: When we apply a force on a body, we say that we are exerting some pressure on the surface of the body. For a constant perpendicular force, the pressure is given as $P=\dfrac{F}{A}$. Using this equation check which of the options are correct.

Complete step by step answer:
Let us first understand what is meant by pressure.When we apply a force on a body, we say that we are exerting some pressure on the surface of the body.Pressure exerted on a surface is equal to the force exerted (that is perpendicular to the surface) per unit area. For a constant perpendicular force, the pressure is given as
 $P=\dfrac{F}{A}$ ….. (i),
where $P$ is the pressure, $F$ is the perpendicular force exerted on a surface of area $A$.

From the equation we get that for a constant force, if the area of the surface is reduced then the pressure on that area will increase and vice versa. Therefore, the blade of an ice-skating shoe is made very sharp. As a result, the surface area of the blade is minimum and the pressure exerted on the ice floor due to the weight of the skater is maximum. Due to which, the skater gets a better grip on the ice. Therefore, option A is correct.

The area of the tip of a nail is made sharp so that with less force, we can exert large pressure on the wood and it is easier to drive the nail into the wood. Therefore, option B is also correct. Similarly, if we have a sharp knife, then the area of the edge of the knife is minimum and therefore, it will exert maximum pressure. Therefore, option C is also correct. In the case of building, the pressure exerted on the ground due to the weight of the building should be minimum. Therefore, its foundation is made wide so that it has a large base and area and the pressure on the ground is very less.

Hence, the correct options are A, B, C, D.

Note:Some students may think that pressure is a vector quantity because it involves force, which is a vector. However, pressure is a scalar quantity. This is because while calculating the pressure we only consider the magnitude of the component of the force that is perpendicular to the surface.