Consider a beaker placed in an elevator that is accelerating upward. In the beaker, assume there is a thin cylinder of height h with an infinitesimal cross-sectional area. On the liquid contained in this infinitesimal cylinder, three vertical forces act. They are the upward force due to the liquid present below the bottom surface, the downward force due to the liquid above the top surface, and the downward force due to its weight. Since the liquid is accelerating, a relation is obtained from Newton's second law. Representing the fluid element's mass in terms of density simplifies the equation, and the expression for pressure difference for accelerating fluid is obtained. Suppose a body is dipped inside the same accelerating liquid. It experiences buoyant force and the force due to its weight. For simplicity, the body is replaced by an equal volume of the same liquid. This makes the entire liquid inside the beaker a homogeneous mass experiencing the same acceleration. From Newton's second law, the buoyant force is expressed in terms of acceleration.