# Fluid Mechanics: Static and Dynamic Pressures

1. A laboratory receives a sample of a metallic alloy composed of aluminum and magnesium. The sample is a solid cylinder with a diameter of 2 cm and a length of 5 cm. Its mass is 15.70 g. What is its density? What is its specific gravity?

2. A boat has a dry weight of 3500 lbs. How many liters of water does it displace?

3. A steel pipe runs vertically from the floor of the ocean to the surface. The pipe is empty -- that is, contains air at atmospheric pressure . What is the water pressure on the pipe 200 m below the surface? At that point, what is the force on 1 cm^2 of the pipe wall? (Density of seawater = 1.03 kg/L)

4. Water is flowing through a circular pipe with an internal diameter of 1 meter, at a rate of 0.5 m3/s. What is the water's flow velocity? What is its dynamic pressure?

5. The static water pressure at point 1 in a pipe is 100 kPa, and the fluid velocity is 2 m/s. At point 2 downstream, the pipe widens and the velocity decreases to 1 m/s. What is the static pressure at that point? The usual assumptions concerning laminar flow, no friction losses, incompressibility, etc. all apply.

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#### Solution Preview

1. density = mass/volume = m/(pi*r^2*l) = 15.70/(3.1415*1^2*5) = 1.00 g/cm^3

specific gravity = density of this sample/density of water = 1.00/1.00 = 1

2. F = mg = density*volume*g, volume = m/density = ...

#### Solution Summary

The expert examines static and dynamic pressures for fluid mechanics.