Question

As a child walks, for a brief moment his entire weight is placed on one heel, which can be approximated as a small circle. Calculate the pressure exerted on the floor by the heel if the circle created by the heel has a diameter of 7 cm, and the child’s mass is 25 kg.Group of answer choices

Answer 1

The correct answer is option b, 63.6 kPa

Given,

The diameter of the heel, d=7 cm=0.07 m

The mass of the child, m=25 kg

The pressure is given by the ratio of the force to the area through which the force is applied.

The force applied on the floor by the child is equal to its weight.

Thus the pressure applied on the floor by the child is given by,

$\begin{gathered} P=\frac{F}{A} \\ =\frac{mg}{\pi(\frac{d}{2})^2} \end{gathered}$

Where A is the area of the cross-section of the heel.

On substituting the known values,

$\begin{gathered} P=\frac{25\times9.8}{\pi(\frac{0.07}{2})^2} \\ =63.6\times10^3\text{ Pa} \\ =63.6\text{ kPa} \end{gathered}$

Thus the pressure applied on the floor by the heel is 63.6 kPa