FLUID MECHANICS 01

91問 • 1年前

問題一覧

If the specific gravity of a certain oil is 0.82, calculate the specific weight.

A. 51.2 lb/𝑓𝑡3

What is the value of the surface tension of a small droplet of water 0.3 mm in diameter which is in contact with air if the pressure within the droplet is 561 Pa?

A. 0.042 N/m

If the specific volume of a certain fluid is 0.7848 𝑚³/𝑘𝑔. What is the specific weight?

A. 12.5 N/𝑚³

Ice in an iceberg has a specific gravity of 0.922. When floating in seawater (specific gravity ═ 1.03), its exposed volume % is nearest to ____________.

D. 10.5

What is the hydraulic radius of the trapezoid (isosceles) irrigation canal of bases 5 m and 11 cm respectively with depth of 4 m?

C. 2.13 m

Answer:

A. 457.45 in.

Convert a vacuum pressure of 110 mm of mercury into absolute pressure if atmospheric pressure is 10.5 meters of water.

C. 88.3 kPa

There are two fluids in an open-end manometer. Fluid 1 is glycerin (12.4 𝑘𝑁/𝑚³), 70 mm below the closed end and fluid 2 is carbon tetrachloride (15.57 𝑘𝑁/𝑚³) which is 150 mm above fluid 1. If the open end is exposed to the atmosphere at 101.325 kPa, what is the absolute pressure at the closed end of the manometer if it is occupied by fluid 1?

A. 102.79 kPa

To what height will a barometer column rise if the atmospheric conditions are 13.9 psia and 68 ℉ and barometer fluid is mercury?

A. 28.3 in.

If the pressure in the air space above an oil (S.G. ═ 0.75) surface in a closed tank is 115 kPa absolute. What is the pressure 2 meters below the surface?

A. 129.72 kPa

A surface tension force, 𝜎, of water in air is approximately 0.00518 lbf/ft. If the atmospheric pressure is 14.7 psia, what is the pressure inside a droplet 0.01” in diameter?

C. 14.87 psia

A cylinder weights 150 lbf and its cross-sectional area is 40 square inches. When the cylinder stands vertically on one end, what pressure does the cylinder exert on the floor?

B. 25.8 kPa

Estimate the height to which water will rise in capillary tube of diameter 5 mm if the surface tension is 0.0728 N/m and the contact angle is 0 °?

A. 5.94 mm

A floating cylinder 8 cm in diameter and weighing 950 grams is placed in a cylindrical container 20 cm in diameter partially full of water. The increase in the depth of water in the container due to placing the float in it is:

C. 3 cm

What is the pressure 8000 ft below the water surface of the ocean? Neglect compressibility.

A. 512,000 psf

Water in the hydraulic press, initially at 137 kPa abs is subjected to a pressure of 116,280 kPa abs. Using E ═ 2.5 Gpa, determine the percentage decrease in the volume of the water.

A. 4.65 %

If the viscosity of water at 70℃ is 0.00402 poise and its specific gravity is 0.978, determine its kinematic viscosity in 𝑐𝑚²/s.

A. 4.11 × 10^-3 𝑠𝑡𝑜𝑘𝑒

Estimate the height to which water will rise in a capillary tube 2 mm in diameter. Use 𝜎 = 0.0728 𝑁/𝑚 𝑎𝑛𝑑 𝛾 = 9810 𝑁/𝑚³.

A. 9.9 mm

Compute the capillary depression for mercury in a glass capillary tube 2 mm in diameter if the surface tension of mercury is 0.514 N/m and 𝜃 = 140 °.

C. 5.9 mm

At a height of 10,000 m (33,000 ft) above the sea level, atmospheric pressure is about 210 mm of Hg. What is the resultant normal force on a 600 𝑐𝑚² window of an airplane flying at this height when the hydrostatic conditions and a pressure inside the plane of 760 mm of mercury and density of mercury is 13,600 𝑘𝑔/𝑚³.

A. 4.403 kN

A barrel contains a 0.150 m layer of oil floating on water that is 0.30 mm deep. If the density of the oil is 600 𝑘𝑔/𝑚³, what is the pressure (gage) at the oil-water interface?

A. 883 Pa

An atmospheric pressure of 101.325 kPa will be supported by how much height of water?

A. 10.32 m

An atmospheric pressure of 101.325 kPa will be supported by how much height of mercury (s.g ═ 13.6)?

B. 0.76 m

A hydraulic lift is to be used to lift a truck weighing 5000 lb. What is the pressure (gage) must be applied to the oil if the diameter of the large piston is 12 in.?

A. 44.2 psi

How high does mercury barometer stands on a day when atmospheric pressure is 98.6 kPa considering that the specific gravity of mercury is 13.6?

A. 739 mm

A rigid container is closed at one end and measures 8 in. diameter by 12 in. long. The container is held vertically and is slowly moved downward until the pressure in the container is 15.5 psia. What will be the depth of the water surface measure from the free water surface?

C. 22 in.

How far below the water surface should a vertical square 1 m on a side with two sides horizontal to be immersed so that the center of pressure will be 70 mm below the center of gravity?

A. 0.69 m

A 0.50 m diameter window has its center three meters below the water surface. Determine the force acting on the window considering the window is submerged vertically.

A. 5.8 kN

A vertical sliding gate is being submerged in a 10-meter water. The gate is 5 m wide and 9 m high and weighs 50 kN. What vertical force is needed to just lift this gate considering that the coefficient of friction between the guides and edges is 0.25? (Note: Neglect buoyant force).

C. 657 kN

The fluid in a manometer tube is 60 % water and 40 % alcohol (S.G ═ 0.8). What is the manometer fluid height difference if a 6.2 psi pressure is applied across the two ends of a manometer?

B. 215 in.

Answer:

D. 10 kN

A vacuum pump is used to drain a flooded mine shaft of 69 ℉ water. The vapor pressure of water at this temperature is 0.34 psi. The pump is incapable of lifting the water higher than 400 inches. What is the atmospheric pressure?

A. 14.78 psi

The density of water is typically taken to be 62.4 𝑙𝑏𝑚/𝑓𝑡³ for engineering problems where greater accuracy is not required. What is the value is 𝑠𝑙𝑢𝑔𝑠/𝑓𝑡³ ?

B. 1.94 𝑠𝑙𝑢𝑔𝑠/𝑓𝑡³

An ice berg has a density of 57.1 𝑙𝑏/𝑓𝑡³. If it floats fresh water, what percent of the iceberg's volume will be visible?

B. 8.5 %

What is the sea level (g ═ 32.2 𝑓𝑡/𝑠²) specific weight ( 𝑙𝑏/𝑓𝑡³) of liquid with density of 58.3 𝑙𝑏/𝑓𝑡³ ?

B. 58.3

What is the pressure of 8000 ft below the ocean surface?

A. 514,176 𝑙𝑏𝑓/𝑓𝑡²

A water-tight, cubical, 12 inches outside dimensions, is made from ¼ inch iron plate. If SG ═ 7.7 for the iron, will the box float?

D. The box will float

Calculate the pressure at a depth of 100 meters in seawater, for which the specific weight is 10.1 𝑘𝑁/𝑚³.

D. 1010 kPa

What is referred to as friction within a fluid that prevents the fluid from flowing freely?

B. Viscosity

If a depth of liquid of 1 m causes a pressure of 7 kPa, what is the specific gravity of the liquid?

B. 0.714

What is the pressure 12.5 m below the ocean?

C. 126.3 kPa

Find the absolute pressure is kPa at a depth of 10 meters below the free surface of oil of sp. gr. 0.75 if the barometer reading is 752 mmHg.

A. 173.9 kPa

If the atmospheric pressure is 95.7 kPa and the gage attached to the tank reads 188 mmHg in vacuum, find the absolute pressure within the tank.

A. 70.62 kPa

A pressure of 35 kPa is measured 4 m below the surface of an unknown liquid. What is the specific gravity of the liquid?

B. 0.89

How high does mercury barometer stand on a day when atmospheric pressure is 98.6 kPa considering that the specific gravity of mercury is 13.6.

A. 739 mm

The length of pipe is 168 meters. If the pressure drop is 50 kPa for every 30 m, what is the total pressure drop?

C. 280 kPa

A balloon having a mass of 400 kg remains suspended motionless in the air. If the air density is 1.29 𝑘𝑔/𝑚³, what is the volume of the balloon in cubic meters?

A. 310 𝑚³

Which of the following refers to the measure of the fluid’s resistance to flow when acted upon by an external force?

D. Viscosity

Which of the following statements is NOT correct?

C. The Reynolds number is the ratio of the viscous force to the inertial force.

Density in terms of viscosity is ________.

B. Dynamic viscosity / kinematic viscosity

Liquids and gases take the following characteristic(s) of their contents.

C. Shape

Which of the following statements about a Newtonian fluid is most accurate?

D. Shear stress is proportional to rate of strain

The normal stress is the same in all directions at a point in fluid:

B. When there is no motion of one fluid layer relative to an adjacent layer

Under which condition, the specific weight of water is 1000 𝑘𝑔/𝑚³ ?

D. All of these

A vena contracta in a fluid jet issuing through a hole in a plate is located approximately:

B. At jet’s minimum diameter

For a partially submerged objects to be stable, where does the metacenter be located?

A. Above the center of gravity

A hydrometer scale for measuring the relative density (specific gravity) of liquids.

C. Baume scale

It refers to the fractional change in the volume of a fluid per unit change in pressure in a constant temperature process. Which one?

B. Compressibility

An instrument which is used to determine the specific gravity of a substance?

A. Hydrometer

Which of the following statements is TRUE about a fluid?

C. It cannot sustain a shear force at rest

Which of the following is an absolute property of liquid?

A. Density

Which of the following is not a unit of viscosity?

D. Baume

What is the pressure at point A in the tank if h ═ 2 m?

D. 20 kPa

What do you call the pressure which the fluid exerts on an immersed object or container walls?

C. Hydrostatic pressure

Viscosity for a fluid is define as the constant of proportionality between shear stress and what other variable?

A. The spatial derivative of velocity

SI unit of viscosity Pa-s is:

A. 10 times poise

Answer:

A. 10 kN

Assuming normal barometric pressure, how deep in the ocean is the point where an air bubble, upon reaching the surface, has five times its volume than it had at the bottom?

A. 40.1 m

The hydraulic radius of noncircular pipe is:

B. The ratio of the area to the wetted perimeter

Absolute viscosity of a fluid varies with the pressure and temperature and is defined as a function of ____________.

C. Shear stress and angular deformation rate

According to Archimedes’ principle, the buoyant force on a submerged object is equal to which of the following?

B. Weight of the displaced fluid

On a stationary floating object, the buoyant force acts upward through the centroid of the displaced volume. What do you call this centroid?

B. Center of buoyancy

In tubes having very small diameters, liquids are observed to rise or fall relative to the level of the surrounding liquid. What do you call this phenomenon?

C. Capillarity

The following are the basic components of a fluid element in motion. Which one is NOT included?

C. Twist

Which of the following is the dominating cause of viscosities of liquids?

A. Molecular cohesion

This principle states that where the velocity of a fluid is high, the pressure is low, and where the velocity is low, the pressure is high. Which one?

A. Bernoulli’s principle

Viscosity for a fluid is define as the constant of proportionality between shear stress and what other variable?

A. The spatial derivative of velocity

What is the atmospheric pressure on a planet if the absolute pressure is 100 kPa and the gage pressure is 10 kPa?

C. 90 kPa

Which of the following devices is used for measuring the absolute pressure of the atmosphere?

C. Barometer

A load from a faucet comes out in separate drops. Which of the following is the main cause of this phenomenon?

B. Surface tension

A 100 g of water are mixed with 150 g of another fluid (𝑝 = 790 𝑘𝑔/𝑚³). What is the specific volume of the resulting mixture, assuming that the volumes are additive and the mixture is homogenous?

C. 0.86 𝑐𝑚³/𝑔

Kinematic viscosity can be expressed in which of the following units?

A. 𝑚³/𝑠

Which of the following does not affect the rise and fall of liquid in a small-diameter capiliary tube?

D. Viscosity of liquid

What is the approximate total pressure of the air inside the container?

C. 103.5 kPa

Archimedes established his principle while investigating a suspected fraud in the construction of a crown. The crown was made from an alloy of gold and silver instead of pure gold. Assume that the volume of the alloy was the combined volumes of the components (the density of gold is 19.3 𝑔/𝑐𝑚³ the density of silver is 10.5 𝑔/𝑐𝑚³). If the crown had a weight of 1000 g in air and 940 g in pure water, what percentage of gold (by weight) was it?

C. 81.2 %

Which of the following statements concerning buoyancy are false? I. Buoyance is the tendency of a fluid to exert a supporting force on a body placed in that fluid. II. Buoyancy is the ability of a body to return to its original position after being titled on its horizontal axis. III. The buoyant force is measured by multiplying the specific weight of the object by the displaced volume of the fluid. IV. Buoyant forces occur both when an object floats in a fluid and when an object sinks in a fluid. V. The buoyant force acts vertically upward through the centroid of the displaced volume.

D. II and III

What is the depth of the center of pressure on the vertical plate if the upper edge is 1.5 m below the water surface?

D. 2.63 m

A pressure vessel with an internal pressure, p is connected to the simple U-tube open to the atmosphere as shown. A 10 cm deflection of mercury is observed. The density of mercury is 13.6 𝑀𝑔/𝑚³. What is most nearly the pressure p, if the atmospheric pressure is 101 kPa?

B. 13 kPa

The surface tension of water is 0.07 N/m. Find the weight of water supported by surface tension in a capillary tube with radius of 0.10 mm.

A. 44 𝜇𝑁

How far below the water surface should a vertical square 1 m on a side with two sides horizontal to be immersed so that the center of pressure will be 70 mm below the center of gravity?

A. 0.69 m

A mercury barometer stands 762 mm. A gas bubble, whose volume is 33 𝑐𝑚³ when it is at the bottom of the lake 45.7 m deep rises to the surface. Compute the volume at the surface of the lake.

A. 178 𝑐𝑚³

Machine Design ( 1st Set )

Jacky Shane Luyas Buhia · 20問 · 2年前

Machine Design ( 1st Set )