In the analysis of the flow velocity of a fluid for a fixed instant of time, a space curve drawn such that it is tangent everywhere to the velocity vector is known as a:

The ratio of the specific weight of a liquid to the specific weight of a standard fluid is known as:

The magnitude of the buoyant force depends on the _____________.

In incompressible fluid dynamics, the continuity equation is ∂u/∂x + ∂v/∂y + ∂w/∂z = 0. What physical law does this equation represent?