What is the effect of pressure of a human body on sand ?

Pressure is defined as the force acting per unit area [4]. In the case of a human body on sand, the force (thrust) is the weight of the person, which remains constant regardless of posture [1]. However, pressure is inversely proportional to the area of contact [2]. When a person is standing, the weight is distributed over the relatively small area of the feet, resulting in high pressure that causes the person to sink deeper into the sand [1]. Conversely, when lying down, the same weight is distributed over a much larger surface area of the entire body, significantly reducing the pressure exerted on the sand [2]. Therefore, the pressure is larger while standing than while lying, as the concentration of force is greater on the smaller contact area [2].

Sources

1. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > 6.1 Pressure > p. 82
2. [4] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > Snapshots > p. 94
3. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > Keep the curiosity alive > p. 95