Bouyancy

Consider all the forces on a submerged object. First, consider a symmetric cylinder like the one pictured here. The horizontal forces cancel each other -- simply from symmetry.

The force due to the fluid on the bottom pushes up.

The force due to the fluid on the top pushes down.

The weight of the object, of course, is down.

F_net = F_bottom - F_top - W_object

F_net = P_bottom A - P_top A - W_object

F_net = ( P_bottom - P_top ) A - W_object

F_net = ( g h ) A - W_object

F_net = g ( h A ) - W_object

F_net = g ( V ) - W_object

F_net = g ( m_liquid ) - W_object

F_net = w_liquid - W_object

F_net = F_bouyant - W_object

F_bouyant = w_liquid

The bouyant force is equal to the weight of the liquid displaced. This is directly related to the fact that pressure increases with depth.

The bouyant force is equal to the weight of the liquid displaced.

Click here for an EXAMPLE.

Pascal's Principle			Fluid Flow
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(c) 2005, Doug Davis; all rights reserved