Exam 9: Solids and Fluids

A crane lifts a steel submarine (density = 7.8 × 10³ kg/m³) of mass 20,000 kg. What is the tension in the lifting cable: (a) when the submarine is submerged? (b) when it is entirely out of the water?

The pressure differential across a wing cross section due to the difference in air flow is explained by

"Pressure applied to an enclosed fluid is transmitted to every point in the fluid and to the enclosure walls" is known as

When a tube of diameter d is placed in water, the water rises to a height h. If the diameter were half as great, how high would the water rise?

What is the maximum depth from which a pump on the surface can "suck" up water?

Consider a submarine at a depth of 67. meters in sea water (density 1.03 grams/cc) and the interior of the sub is at 1.0 atmosphere. (a) What is the outside pressure at that depth? (b) Find the total force that must be withstood by a square hatch (0.90 m square) which leads to the sub interior.

COHESIVE FORCES are

Instead of cables, a hydraulic lift raises an elevator weighing 2.5 kiloNewtons. The input piston has a 2.0 cm diameter and the lift piston has a 28. cm diameter (See Figure 9-3) What minimum force must be applied to the input piston?

Stress is

A wire of diameter 1.0 mm and length 3.5 m stretches 3.5 mm when 8.0 kg is hung from it. (a) What is the Young's modulus for the wire? (b) What is the effective spring constant for the stretching wire?

Consider an object floating on a pool of water. Suppose much oil is poured onto the water and now floats above the water, with the object floating with part surrounded by a layer of oil and the lower part still in water. How has the buoyant force on the object changed by the oil layer?

Incompressible flow means that the fluid's density is constant.

Suppose that the build-up of fatty tissue on the wall of an artery decreased the radius by 10%. By how much would the pressure provided by the heart have to be increased to maintain a constant blood flow?

Oil of specific gravity 0.90 is poured on top of a beaker of water. A cube of plastic of specific gravity 0.95 is placed in the liquid. What fraction of the cube will be immersed in water?

Distinguish between stress and strain.

A piece of iron sinks to the bottom of a lake where the pressure is 21 atm. Which statement best describes what happens to the density of that piece of iron?

Water flows through a horizontal pipe of cross-sectional area 10. cm² at a pressure of 0.25 atm. The flow rate is 1.0 L/s. At a valve, the effective cross-sectional area of the pipe is reduced to 5.0 cm². What is the pressure at the valve?

At a depth of about 1030. m in the sea the pressure has increased by 100. atmospheres (to about 10⁷ N/m²). By how much has 1 m³ of water been compressed by this pressure? The bulk modulus of water is 2.3 × 10⁹ N/m².

A window for viewing fish in the local aquarium is square and measures 0.8 m × 0.8 m. Its center is 12. m below the surface. What is the total force on the window?

If a liquid does not wet the inner surface of a capillary tube inserted into it, the cohesion of the liquid is ________ the adhesion between the liquid and surface.