CENTER OF PRESSURE APPARATUS

The Centre of Pressure Apparatus has been designed to determine the static thrust exerted by a fluid on a submerged surface and allow comparison of the measured magnitude and position of this force with simple theory.
A fabricated quadrant is mounted on a balance arm, which pivots on knife-edges. The knife-edges coincide with the centre of arc of the quadrant. Thus, of the hydrostatic forces acting on the quadrant when immersed, only the force on the rectangular end face gives rise to a moment about the knife-edges. The balance arm incorporates a balance pan for the weights supplied and an adjustable counterbalance. This assembly is mounted on top of an acrylic tank, which may be levelled by adjusting screwed feet. An indicator attached to the side of the tank shows when the balance arm is horizontal. Water is admitted to the top of the tank by a flexible tube and may be drained through a cock in the side of the tank. The water level is indicated on a scale on the side of the quadrant.