Fluid

• Gases may be distinguished from other forms of matter by their:

  A. lack of color

  B. small atomic weights

  C. inability to form free surfaces

  D. ability to flow

  E. ability to exert a buoyant force

  ans: C
• 3. 1 Pa is:

  A. 1 N/m

  B. 1 m/N

  C. 1 kg/m · s

  D. 1 kg/m · s2

  E. 1 N/m · s

  ans: D
• 4. Mercury is a convenient liquid to use in a barometer because:

  A. it is a metal

  B. it has a high boiling point

  C. it expands little with temperature

  D. it has a high density

  E. it looks silvery

  ans: D
• 5. To obtain the absolute pressure from the gauge pressure:

  A. subtract atmospheric pressure

  B. add atmospheric pressure

  C. subtract 273

  D. add 273

  E. convert to N/m2

  ans: B
• 6. Barometers and open-tube manometers are two instruments that are used to measure pressure.

  A. Both measure gauge pressure

  B. Both measure absolute pressure

  C. Barometers measure gauge pressure and manometers measure absolute pressure

  D. Barometers measure absolute pressure and manometers measure gauge pressure

  E. Both measure an average of the absolute and gauge pressures

  ans: D
• 7. To measure moderately low pressures oil with a density of 8.5 × 102 kg/m

  3 is used in place of

  mercury in a barometer. A change in the height of the oil column of 1.0 mm indicates a change

  in pressure of about:

  A. 1.2 × 10−7 Pa

  B. 1.2 × 10−5 Pa

  C. 0.85 Pa

  D. 1.2 Pa

  E. 8.3 Pa

  ans: E
• 8. The pressure exerted on the ground by a man is greatest when:

  A. he stands with both feet flat on the ground

  B. he stands flat on one foot

  C. he stands on the toes of one foot

  D. he lies down on the ground

  E. all of the above yield the same pressure

  ans: CSee an-written !We h
• 10. In a stationary homogeneous liquid:

  A. pressure is the same at all points

  B. pressure depends on the direction

  C. pressure is independent of any atmospheric pressure on the upper surface of the liquid

  D. pressure is the same at all points at the same level

  E. none of the above

  ans: D
• 11. Which of the following five statements, concerning the upper surface pressure of a liquid, is

  FALSE?

  A. It is independent of the surface area

  B. It is the same for all points on that surface

  C. It would not increase if the liquid depth were increased

  D. It would increase if the liquid density were increased

  E. It would increase if the atmospheric pressure increased

  ans: D
• 12. Several cans of different sizes and shapes are all filled with the same liquid to the same depth.

  Then:

  A. the weight of the liquid is the same for all cans

  B. the force of the liquid on the bottom of each can is the same

  C. the least pressure is at the bottom of the can with the largest bottom area

  D. the greatest pressure is at the bottom of the can with the largest bottom area

  E. the pressure on the bottom of each can is the same

  ans: E
• 13. An airtight box, having a lid of area 80 cm2, is partially evacuated. Atmospheric pressure is

  1.01 × 105 Pa. A force of 600 N is required to pull the lid off the box. The pressure in the box

  was:

  A. 2.60 × 104 Pa

  B. 6.35 × 104 Pa

  C. 7.50 × 104 Pa

  D. 1.38 × 105 Pa

  E. 1.76 × 105 Pa

  ans: A
• 14. A closed hemispherical shell of radius R is filled with fluid at uniform pressure p. The net force

  of the fluid on the curved portion of the shell is given by:

  A. 2πR2p

  B. πR2p

  C. 4πR2p

  D. (4/3)πR2p

  E. (4/3)πR3p

  ans: B
• 17. A uniform U-tube is partially filled with water. Oil, of density 0.75 g/cm3, is poured into the right arm until the water level in the left arm rises 3 cm. The length of the oil column is then:

  A. 2.25 cm

  B. 8 cm

  C. 6 cm

  D. 4 cm

  E. need to know the cross-sectional area of the U-tube

  ans: B
• 18. A long U-tube contains mercury (density = 14 × 103 kg/m3). When 10 cm of water (density = 1.0 × 103 kg/m3) is poured into the left arm, the mercury in the right arm rises above its original level by:

  A. 0.36 cm

  B. 0.72 cm

  C. 14 cm

  D. 35 cm

  E. 70 cm

  ans: A
• 19. A bucket of water is pushed from left to right with increasing speed across a horizontal surface.

  Consider the pressure at two points at the same level in the water.

  A. It is the same

  B. It is higher at the point on the left

  C. It is higher at the point on the right

  D. At first it is higher at the point on the left but as the bucket speeds up it is lower there

  E. At first it is higher at the point on the right but as the bucket speeds up it is lower there

  ans: B
• 20. A bucket resting on the floor of an elevator contains an incompressible fluid of density ρ. When

  the elevator has an upward acceleration of magnitude a the pressure difference between two

  points in a fluid separated by a vertical distance ∆h, is given by:

  A. ρa∆h

  B. ρg∆h

  C. ρ(g + a)∆h

  D. ρ(g − a)∆h

  E. ρga∆h

  ans: C
• 21. A bucket resting on the floor of an elevator contains an incompressible fluid of density ρ. When

  the elevator has a downward acceleration of magnitude a the pressure difference between two

  points in a fluid, separated by a vertical distance ∆h, is given by:

  A. ρa∆h

  B. ρg∆h

  C. ρ(g + a)∆h

  D. ρ(g − a)∆h

  E. ρga∆h

  ans: D
• 22. "An object completely submerged in a fluid displaces its own volume of fluid". This is:

  A. Pascal's paradox

  B. Archimedes' principle

  C. Pascal's principle

  D. true, but none of the above

  E. false

  ans: D
• 23. A certain object floats in fluids of density

  1. 0.9ρ0

  2. ρ0

  3. 1.1ρ0

  Which of the following statements is true?

  A. the buoyant force of fluid i is greater than the buoyant forces of the other two fluids

  B. the buoyant force of fluid 3 is greater than the buoyant forces of the other two fluids

  C. the three fluids exert the same buoyant force

  D. the object displace the same volume of all three fluids

  E. none of these are true

  ans: C
• 24. A certain object floats in fluids of density

  1. 0.9ρ0

  2. ρ0

  3. 1.1ρ0

  Rank these fluids according to the volume displaced by the object, least to greatest.

  A. 1, 2, 3

  B. 3, 2, 1

  C. 2, 3, 1

  D. 3, 1, 2

  E. All are the same

  ans: B
• 26. A block of ice at 0◦ C is floating on the surface of ice water in a beaker. The surface of the

  water just comes to the top of the beaker. When the ice melts the water level will:

  A. rise and overflow will occur

  B. remain the same

  C. fall

  D. depend on the initial ratio of water to ice

  E. depend on the shape of the block of ice

  ans: B
• 27. A block of ice at 0◦ C containing a piece of cork is floating on the surface of ice water in a

  beaker. When the ice has melted the water level:

  A. is higher

  B. is lower

  C. is the same

  D. depends on the initial ratio of water to ice

  E. depends on the shape of the ice block

  ans: C
• 28. A pirate chest rests at the bottom of an ocean. If the water is still, the net force it exerts on

  the chest:

  A. is upward

  B. is downward

  C. is zero

  D. depends on the mass of the chest

  E. depends on the contents of the chest

  ans: B
• 29. A small steel ball floats in a half-full container of mercury. When water is added:

  A. the ball will float on the water

  B. the ball will rise slightly

  C. the mercury will float on the water

  D. the ball will sink to the bottom of the container

  E. the ball will lower slightly more into the mercury

  ans: B
• 30. A cork floats on the surface of an incompressible liquid in a container exposed to atmospheric pressure. The container is then sealed and the air above the liquid is evacuated. The cork:

  A. sinks slightly

  B. rises slightly

  C. floats at the same height

  D. bobs up and down about its old position

  E. behaves erratically

  ans: C
• 31. An object hangs from a spring balance. The balance indicates 30 N in air and 20 N when the

  object is submerged in water. What does the balance indicate when the object is submersed

  in a liquid with a density that is half that of water?

  A. 20 N

  B. 25 N

  C. 30 N

  D. 35 N

  E. 40 N

  ans: B
• 32. A fir wood board floats in fresh water with 60% of its volume under water. The density of the

  wood in g/cm3 is:

  A. 0.4

  B. 0.5

  C. 0.6

  D. less than 0.4

  E. more than 0.6

  ans: C
• 33. A boat floating in fresh water displaces 16, 000 N of water. How many newtons of saltwater

  would it displace if it floats in saltwater of specific gravity 1.17?

  A. 14, 500

  B. 17, 600

  C. 16, 000

  D. 284

  E. 234

  ans: C
• 34. A rock, which weighs 1400 N in air, has an apparent weight of 900 N when submerged in fresh water (998 kg/m3). The volume of the rock is:

  A. 0.14 m3

  B. 0.60 m3

  C. 0.90 m3

  D. 5.1 × 10−2 m3

  E. 9.2 × 10−2 m3

  ans: D
• A U-tube contains two liquids that do not mix. One of the liquids has a density of 1200 kg/m3while the other liquid has a density of 900 kg/m3. Using the information from the figure, what is the height of the indicated liquid column on the right? A) 2 cm B) 3 cm C) 4 cm D) 5 cm E) 6 cm

  E
• Water flows through a cylindrical pipe of varying cross-section. The velocity is 2.0 m/s at a point where the pipe’s diameter is 2.0 cm. What is the diameter of the pipe at a point in which the velocity is 8.0 m/s? A) 0.5 cm B) 1.0 cm C) 2.0 cm D) 4.0 cm E) 8.0 cm

  B
• Water flows through a cylindrical pipe of varying cross-section. The velocity is 3.0 m/s at a point where the pipe’s diameter is 1.0 cm. What is the velocity of the water at a point where the pipe diameter is 3.0 cm? A) 9 m/s B) 0.33 m/s C) 3 m/s D) 1 m/s E) 0.11 m/s

  B
• A hydraulic press has one piston of diameterD1 = 2.0 cm and another piston of diameter D2 = 8.0 cm. What force must be applied to the smaller piston to lift a package with a mass ofM2 = 160 kg placed on the larger piston? A) 50 N B) 100 N C) 400 N D) 1,600 N E) 6,400 N

  B
• The diagram shows a U-tube with cross-sectional area A and partially filled with oil of density p. A solid cylinder, which fits the tube tightly but can slide without friction, is placed in the right arm. The system is in equilibrium. The weight of the cylinder is: A. ALpg B. L³pg C. Ap(L+h)g D. Ap(L-h)g

  ALpg
• The density of water is 1.0g/cm^3. The density of the oil in the left column of the U-tube shown below is: A. 0.20 B. 0.80 C. 1.0 D. 1.3

  0.80 g/cm^3
• A rock, which weighs 1400 N in air, has an apparent weight of 900 N when submerged in fresh water (998 kg/m^3). The volume of the rock is: A. 0.14 B. 0.5 C. 0.9 D. 5.1x10^-2 E. 9.2x10^-2

  5.1 x 10^-2 m^3
• The dimensions of a wooden raft (density = 150 kg/m^3) are 3.0m x 3.0m x 1.0m. What maximum load can it carry in seawater (density = 1020 kg/m^3)? A. 1350kg B. 7800kg C. 9200kg D. 19,500kg E. 24,300kg

  7800kg
• A tin can has a volume of 1000 cm^3 and a mass of 100g. Approximately what mass of lead shot can it carry without sinking in water? A. 900g B. 100g C. 1000g D. 1100g

  900 g
• A block of wood weighs 160 N and has a specific gravity of 0.60. To sink it in fresh water requires an additional downward force of: A. 54N B. 64N C. 96N D. 110N E. 240N

  110 N
• A solid has a volume of 8 cm^3. When weighed on a spring scale calibrated in grams, the scale indicates 20g, What does the scale indicate if the object is weighed while immersed in a liquid of density 2g/cm^3? A. 10g B. 12g C. 4g D. 16g

  4g