Fluid Mechanics - 5 Steps to a 5 500 AP Physics Questions to Know by Test Day

5 Steps to a 5 500 AP Physics Questions to Know by Test Day (2012)

Chapter 11. Fluid Mechanics

301. A syringe has an interior diameter of 2 cm and a 20-gauge needle with a nominal inside diameter of 0.603 mm is attached. If the nurse presses on the syringe plunger with 1 N, what will be the pressure in the needle?

(A) 1,100 Pa

(B) 3,180 Pa

(D) 0.32 Pa

(E) 110 Pa

302. The city water tank is filled from a well. The tank is placed on a 4-m-high hill in the center of the town. The town is mostly at sea level except for the hill. The tank is 25 m tall with the water level maintained by the pump at 24.5 m. What is the water pressure at Mrs. Jones’ sink, which has the faucets at 1 m from the ground?

(A) 284,000 Pa

(B) 245,000 Pa

(D) 240,000 Pa

(E) 279,000 Pa

303. A drain valve failed in the town’s sewer system, and sewage backed up into the system. The 50-kg, 1-m-diameter manhole covers began popping off. What was the pressure in the sewer system to cause this phenomenon?

(A) 64,000 Pa

(B) 490 Pa

(D) 620 Pa

(E) 640,000 Pa

304. A glass is filled with water to the brim. Ice is placed in the glass. Will the water overflow, remain the same, or decrease when the ice is added? (Density of water is 9,800 N/m³ and 9,000 N/m³ for ice.)

(A) The water will overflow as the ice melts.

(B) The water will decrease.

(D) The water will overflow.

(E) The water will decrease as the ice melts.

305. Evangelista Torricelli found that his mercury barometer had a column of mercury 760 mm/Hg at his town of Faenza, Italy, which is 50 m above sea level. That same day, he took his barometer into the mountains west of town and found that the mercury column was 720 mm/Hg. When he returned to Faenza, it was raining and the column remained the same. Why? (Assume the temperature remained the same.)

(A) The air density changed.

(B) Some of the mercury evaporated.

(D) The lower air density in the mountains caused the mercury column to decrease.

(E) The rain dissolved some of the mercury.

306. In a famous 1654 experiment, Otto von Guericke cast two halves of a 51-cm-diameter sphere. He fit them together so the sphere would not leak, and then he evacuated it. Two teams of eight horses could not pull the hemispheres apart. Later, he tried two teams of 12 horses, but they still could not pull the hemispheres apart. If the sphere was evacuated to 0.1 atmospheres, what force would be required to pull the hemispheres apart?

(A) They cannot be pulled apart by horses

(B) 20,000 N

(D) 74,555 N

(E) 149,000 N

307. A rock is placed on a boat in a swimming pool. If the rock is taken from the boat and dropped into the pool, what will happen to the water level in the pool?

(A) The water level will rise.

(B) The water level will fall.

(D) The water level will fall as the rock dissolves.

(E) The water level depends on the size of the rock.

308. Coming home from Greece in the early 1800s, Lady Elgin’s ship sank in the Mediterranean with the famous Elgin marbles aboard. British Navy divers searching for the vessel used a weighted 5,000-L wine barrel with an open bottom as a diving bell in which to rest and get air. If the ship was 30 m under water, how much weight must be added to the barrel to sink it to the sunken ship’s level? (The density of Mediterranean seawater is 1,029kg/m³. The volume of wood used in the barrel is ignored, and the air in the barrel is maintained by pumps of 5,000 L.)

(A) 50,400,000 N

(B) 5,040,000 N

(D) 4,900,000 N

(E) 11,334,640 pounds

309. Each of the caryatids on Lady Elgin’s sunken ship weighed 50,000 N. The salvage ship displaces 75 m³ for each 0.5 m on the ship’s load line. When all four had been hoisted aboard the salvage ship, how much lower in the water did it ride?

(A) 2.6 cm

(B) 1.3 cm

(D) 1.3 m

(E) 2.6 m

310. At Barone Dam, the water intake is 7 m in diameter. It narrows to 2 m in the turbine room and increases to 3 m in diameter at the downstream outlet. Using a pitot tube, an engineer measures the outlet flow as 50,000 L/s. What is the water’s velocity at each of the three points?

(A) 10, 20, 1 m/s

(B) 7, 16, 1 m/s

(D) 20, 30, 40 m/s

(E) 10.05, 20.36, 30.56 m/s

311. A 2-ton jack uses a pump to force hydraulic oil into a jack cylinder. With each stroke, the pump moves 5 cc of oil into the 3-cm-diameter jack cylinder. How high does the jack rise with each stroke?

(A) 0.71 cm

(B) 71 cm

(D) 1 cm

(E) 1.07 cm

312. Each of two journal bearings on a ball mill has an area of 2 m². The ball mill weighs 270,000 N. At what pressure must oil be injected into a journal bearing to float the ball mill on a film of oil?

(A) 135,000 N/m²

(B) 140,000 Pa

(D) 540,000 N/m²

(E) 134,000 Pa

313. There is a 3-m-tall, open water tank at the King Ranch in Texas. It has a rounded outlet at the bottom and is normally capped. The tank is kept filled to 2.75 m by a pump in a nearby well. A ranch hand stops at the tank to get some water and opens the outlet cap. What is the velocity of the water coming out of the outlet?

(A) 7.4 m/s

(B) 54 m/s

(D) 7.3 m/s

(E) 7 m/s

314. If the outlet of the water tank in Question 313 is 7.5 cm in diameter, will the ranch hand be able to replace the cap on the outlet?

(A) Perhaps, if he has super-human strength

(B) No, because the pressure is too great

(D) No, because the force required to replace the cap is too great

(E) No, because the outlet is too small

315. If the tank in Question 313 was closed and the internal pressure at the outlet was maintained at 690 kPa, what is the outlet velocity when opened?

(A) 1.2 m/s

(B) 37 m/s

(D) 12 m/s

(E) 20 m/s

316. The Roman aqueducts were built with a slope of approximately 30 cm/km. If the water source was 15 km from Rome, what was the pressure in the fountains fed by that aqueduct?

(A) 0.4 Pa

(B) 0.04 Pa

(D) 4.0 Pa

(E) 40.0 Pa

317. Three beakers are placed on a laboratory bench and are filled with water (density: 9,807 N/m³), ethyl alcohol (density: 7,740 N/m³), and sulfuric acid (density: 17,960 N/m³), respectively. One long glass tube is placed in each of the three beakers, with their open ends in the fluid and the other ends connected to a vacuum pump. Given the density of each fluid, how high will each liquid rise in its tube? (Assume standard air pressure, perfect vacuum, neglect friction, vapor pressure, and capillary action.)

(A) 10.3 mm, 13.1 mm, and 5.6 mm, respectively

(B) The vacuum pump will suck up all the liquids to the same height

(D) 10.33 m, 13.1 m, and 5.642 m, respectively

(E) 10.33190 m, 13.091085 m, and 5.641703 m, respectively

318. You are fishing in the local quarry when your friend capsizes the boat while trying to catch a fish. A 45-N bronze fishing trophy, your favorite 225-N maple Captain’s chair, a 230-N block of ice that was to be used to cool the fish, and a 180-N steel bar used to stun the fish are now all in the lake. What is the buoyant force exerted on each of the objects? (The densities are as follows: lake water, 9,807 N/m³; bronze, 858,300 N/m³; maple, 6,300 N/m³; ice, 9,040 N/m³; and steel, 76,500 N/m³.)

(A) Trophy buoyant force, 5.2 kg; chair buoyant force, 350 kg; ice buoyant force, 250 kg; bar buoyant force, 2.3 kg

(B) Trophy buoyant force, 5.2 N; chair buoyant force, 350 N; ice buoyant force, 250 N; bar buoyant force, 2.3 N

(C) Trophy buoyant force, 5.175 N; chair buoyant force, 350.325 N; ice buoyant force, 249.55 N; bar buoyant force, 2.043 N

(D) Trophy buoyant force, 0.52 N; chair buoyant force, 35 N; ice buoyant force, 25 N; bar buoyant force, 2 N

(E) Trophy buoyant force, 52 N; chair buoyant force, 350 N; ice buoyant force, 250 N; bar buoyant force, 23 N

319. Your mother throws her 20-N cast iron skillet into the quarry lake with a rope attached. What is the buoyant force on the skillet? How much force must be applied to the rope to pull up the skillet? (Cast iron has a density of 70,600 N/m³.)

(A) 20 N and 20 N

(B) 0.00028 N and 20 N

(D) 2.8 N and 17.2 N

(E) 28 N and 172 N

320. Why does a siphon work?

(A) Once filled, head pressure causes the liquid to move through the siphon.

(B) Once filled, air pressure and head pressure cause the liquid to move through the siphon.

(D) Torricelli’s law requires it.

(E) Once filled, the intermolecular forces keep the liquid together and then pull the liquid through the siphon.

321. In Question 320, how high can the bend in the siphon be above the liquid level and still work?

(A) Only as high as the atmospheric pressure expressed by the liquid

(B) The bore diameter of the tube divided by the pressure head

(D) Only as high as the pressure head of the liquid

(E) Only as high as the vapor pressure of the liquid

322. How does a toilet work?

(A) Water from the tank pushes the water out of the toilet bowl.

(B) Water from the outlet in the bottom of the toilet bowl pushes the water out of the bowl.

(D) Water flowing through the sewer pipe draws the water out of the bowl.

(E) The tank’s pressure head causes the water in the bowl to gain velocity and move into the sewer pipe.

323. A fire engine produces 700 kPa in a hose with a 3-cm-nozzle bore. How high can the water from the hose reach? (Neglect friction.)

(A) 72 m

(B) 73 m

(D) 71 m

(E) 7.1 m

324. Why will a spring-driven watch run faster in the mountains compared with down at the seashore?

(A) Gravity is low in the mountains so the watch runs faster.

(B) Its potential energy is greater in the mountains so the watch runs faster.

(D) Air in the mountains has less water vapor, the spring moves more easily, and the watch runs faster.

(E) Air in the mountains is less dense, the spring moves more easily, and the watch runs faster.

325. In Philadelphia, two tall buildings are at the corner of Independence Park. When the wind blows from the north, the wind blowing between the two buildings is much faster. Why?

(A) The wind is funneled between the buildings.

(B) The flat area of the park allows the wind to speed up.

(D) Because of the continuity of flow, the air moving between the buildings speeds up.

(E) Because of the conservation of energy, the wind must speed up between the buildings.

326. A U tube using mercury shows a height difference of 200 mm. What is the pressure difference between the two sides of the manometer? (Density of mercury is 133,300 N/m³.)

(A) 27,000,000 Pa

(B) 26,660 Pa

(D) 260,000 Pa

(E) 261,270 Pa

327. A beaker of water is at rest and its water surface is flat. What shapes do the water surface assume when the beaker is rotated around the beaker’s vertical axis, then moved horizontally, and then moved vertically?

(A) Semicircle, inclined, and flat

(B) Semicircle, π/4 angle with the horizontal, and flat

(D) Parabola, inclined, and flat

(E) Parabola, π/4 angle with the horizontal, and flat

328. A sailboat heels to port and puts a 25-cm-diameter porthole 1 m under water. What is the average pressure on the porthole? Will the porthole break?

(A) 110,000 Pa; probably

(B) 11,000 N.m³; probably

(D) 11,000 Pa; probably

(E) 110,000 Pa; probably not

329. A log of cross-sectional Area A is weighted so that it floats vertically in a pond. What is its frequency of oscillation if the friction and the energy imparted to the water are neglected?

330. Given a uniform, open U tube that is partially filled with mercury and free of friction, what is its frequency when the mercury level is caused to oscillate?