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# Flow velocity, Pressure, Buoyancy, Buoyant Force, Lift and Drag

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A pipeline has an entrance diameter of of 2 ft. and an exit diameter of 1 ft. Water flows into the entrance of the pipe at 100 ft/sec. The pressure at the entrance is 200 lb/ft2. Find the velocity and pressure at the exit. (Assume that there is no friction).

A buoyant object is submerged in water. The buoyant force is measured at 5 lb-ft/sec2. When weighed in the open air, the ball weighs 3 lb. (Remember that open air weight is equal to mass times gravity). What is the density of the ball?

You want to compute the values of the water pressure at various depths below the surface of a lake. Compute the water pressure at 50 feet below the surface, 100 feet below the surface, and so on down to 500 feet below the surface. Show the results of your calculations in a table.

Answer the following four related questions:
How is the speed that an airfoil (i.e. a wing) is traveling over the top and bottom surfaces related to the pressure that is exerted on the top and bottom surfaces of the wing?
How is the total pressure resolved into lift and drag.
How does drag affect the velocity of the wing?
How is the height that the airfoil will rise to affected by the weight of the airfoil?

https://brainmass.com/physics/fluid-dynamics/flow-velocity-pressure-buoyancy-buoyant-force-lift-drag-150437

#### Solution Preview

Please see the attached file for the complete solution.

A pipeline has an entrance diameter of 2 ft. and an exit diameter of 1 ft. Water flows into the entrance of the pipe at 100 ft/sec. The pressure at the entrance is 200 lb/ft2. Find the velocity and pressure at the exit. (Assume that there is no friction.)

Sol: A1v1 = A2v2
Therefore, v2 = A1v1/A2 =
P1 + ½ρv12 = P2 + ½ρv22 ==> P2 = ½ ρ( v12 - v22) + P1
ρ = 62.4 lb/ft3
P2 = ½ρ( v12 - v22) + P1 = = -4679800 lb/ft2

A buoyant object is submerged in water. The buoyant force is measured at 5 lb-ft/sec2. When weighed in the open air, the ball weighs ...

#### Solution Summary

Flow velocity, pressure, buoyancy, Buoyant Force, Lift and Drag are investigated. The solution is detailed and well presented.

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