Examples of fluid in the following topics:
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- Pressure is an important quantity in the studies of fluid (for example, in weather forecast).
- For fluids near the surface of the earth, the formula may be written as p=ρgh, where p is the pressure, ρ is the density of the fluid, g is the gravitational acceleration, and h is the depth of the liquid in meters.
- Using this expression, we can calculate the total force that the fluid pressure gives rise to:
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- Imagine that we have a fluid flowing through S, such that v(x) determines the velocity of the fluid at x.
- The flux is defined as the quantity of fluid flowing through S in unit amount of time.
- This illustration implies that if the vector field is tangent to S at each point, then the flux is zero, because the fluid just flows in parallel to S, and neither in nor out.
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- Vector fields are often used to model the speed and direction of a moving fluid throughout space, for example, or the strength and direction of some force, such as the magnetic or gravitational force, as it changes from point to point.
- In the case of the velocity field of a moving fluid, a velocity vector is associated to each point in the fluid.
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- If the vector field represents the flow velocity of a moving fluid, then the curl is the circulation density of the fluid.
- (Note that we are imagining the vector field to be like the velocity vector field of a fluid (in motion) when we use the terms flow, sink, and so on.)
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- The latter is important in many areas of physics, including electromagnetic theory, heat transfer, fluid dynamics, and special relativity.
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- In physics, Green's theorem is mostly used to solve two-dimensional flow integrals, stating that the sum of fluid outflows at any point inside a volume is equal to the total outflow summed about an enclosing area.
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- Vector calculus is used extensively throughout physics and engineering, mostly with regard to electromagnetic fields, gravitational fields, and fluid flow.
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- The divergence theorem is an important result for the mathematics of engineering, in particular for electrostatics and fluid dynamics.