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Physics Grade 12 Unit 3: Fluid Mechanics

national exam questions have come from this unit. It runs 48 pages; one careful study pass takes about 5.8 hours, and its difficulty is moderate among Physics units. Each section below lists the questions set from it, with the year, and opens the page that teaches it.

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3.1 Fluid Statics · read p. 69
  • 2017 E.C., Q26 – At normal condition, solids are almost incompressible compared to liquids and gases. The reason is that
  • 2016 E.C., Q19 – Molar heat capacity of an ideal gas at a constant pressure and constant volume are given by C P and C V respectively. If R is a universal gas constant, which one of the following equation is correct about the relation be
  • 2014 E.C., Q28 – Which of the following statements describe the use of energy resources?
  • 2012 E.C., Q7 – Two moles of an ideal gas at a temperature of $308\,\text{K}$ is confined in a volume of $5.00 \times 10^{-3}\,\text{m}^3$. The pressure of the gas is (Universal gas constant $R= 8.314\,\text{J/mol.K}$).
  • 2011 E.C., Q25 – Which of the following statement is correct? (Here is the density of an ideal gas, is the mass of the gas and is speed of particles ) ρ⟨c ⟩ 2 1 2
  • 2007 E.C., Q25 – An ideal gas undergoes an isothermal process starting with a pressure of $2 \times 10^5\,\text{pa}$ and a volume of $6\,\text{cm}^3$. Which one of the following might be the pressure and volume of the final state?
3.2 Pressure in fluids at rest · read p. 82
  • 2018 E.C., Q22 – Pascal's principle states that a pressure added at the top of a liquid at rest in a cylindrical shape container:
  • 2017 E.C., Q52 – An object dropped into a sea sinks to a depth of 100 m. Which of the following is correct about the pressure the 1030kg/m3 object experiences? (Assume the density of seawater is and the air above the see exerts a P = atm
  • 2017 E.C., Q53 – The atmospheric pressure in a certain area is determined to be $103.36\,\text{kPa}$, using a mercury barometer shown in the figure below. (Acceleration due to gravity, $g = 10\,\text{m}/\text{s}^2$, and density of mercur
  • 2017 E.C., Q30 – A $10\,\text{N}$ force is applied to the smaller circular piston of a hydraulic lift of radius $0.1\,\text{m}$ to lift a $2500\,\text{N}$ load placed on the larger piston. What is the area of the larger piston?
  • 2016 E.C., Q30 – Which one of the following statements is correct about Biot-Savart law?
  • 2015 E.C., Q11 – A fluid travelling over an object's surface exerts less pressure than if the fluid was static. This is a statement of
  • 2013 E.C., Q35 – Ethanol has a surface tension of 22x 10-3 N/m and its density is of 0.789 g/cm3. The radius of the capillary tube is 15 mm, and the contact angle is 30o. Determine the height rise in the column of the capillary tube.
  • 2013 E.C., Q41 – A sample mixture of gas contains 72% of hydrogen and 28% of Helium. What is the partial pressure of helium at an atmospheric pressure of 76 cm of mercury (Hg)?
  • 2012 E.C., Q4 – Which one of the following is NOT true about Pascal's principle and its application?
  • 2009 E.C., Q14 – Which of the following is the application of Pascalᓼs law?
  • 2008 E.C., Q21 – Pressure at the bottom of a liquid column is independent of:
  • 2007 E.C., Q21 – A shaded rectangular block labelled W rests on top of the large piston in the right limb, which sits higher than the small piston.] 3 × 102 2 × 104
  • 2006 E.C., Q6 – Which statement is correct about the pressure under a fluid in a container?
  • 2005 E.C., Q32 – A container resting on the floor of an elevator contains an incompressible fluid of density $\rho$. When the elevator has an upward acceleration of magnitude "$a$" then what will be the pressure difference between two po
  • 2005 E.C., Q20 – A very large open tank is full of oil whose density is 800kg/m. if the absolute pressure at the bottom of the tank 1.81 × 105 1.01 × 105 is Pa, then what is the depth of the oil? (Note that atmospheric pressure is Pa)
3.3 Archimedes’ principle · read p. 96
  • 2017 E.C., Q4 – An object that is partially or fully submerged in a fluid experiences an upward force from the fluid. The apparent weight of the object is the weight of the
  • 2015 E.C., Q27 – A wooden block of volume 5.00 × 10⁻⁴ m³ floats partially submerged in water, and a small steel object of mass m is placed on top of the block. When m = 0.25 kg, the system is in equilibrium and the top of the wooden bloc
  • 2014 E.C., Q29 – According to the law of floatation, an object must displaces a volume of fluid
  • 2010 E.C., Q25 – An object with a mass of 150 kg and a volume of 0.75 is floating in a liquid of density 0.8 . What percentage of the objects volume will be submerged below the surface of the fluid?
  • 2007 E.C., Q20 – Two solid spheres made of gold and silver having equal masses are suspended by strings and fully submerged in a tank of water. Given that the density of gold is greater than that if silver, which one of the following sta
3.4 Fluid flow · read p. 103
  • 2018 E.C., Q24 – Which one of the following statements is correct about the characteristics of steady and turbulent fluid flow?
  • 2017 E.C., Q25 – The flow rate of a fluid is defined as
  • 2011 E.C., Q21 – Water flows at a rate of 0.4 litter per second through garden hose of inside diameter 4.0 cm. The nozzle of the π = 3.14 hose is a circular opening of diameter 2.0 cm. What is the speed of the water when it emerges? ( )
  • 2010 E.C., Q18 – In the figure below, what is the speed of water as it leaves ? [Figure: Shaded drawing of a narrow horizontal pipe on the left feeding into a much wider rectangular chamber A = 1 4 cm2 on the right. On the left, an arrow
  • 2008 E.C., Q22 – A water pipe has a diameter of 5.0cm in the in let side and 1.5cm in the out let side. Water flows at per minute at the in let paint. What is the speed of the water at the out let point?
  • 2007 E.C., Q22 – An incompressible fluid flows through a horizontal pipe whose diameter varies along its length. The sum of the kinetic energy per unit volume and pressure of the fluid at different section of the pipe would________
  • 2005 E.C., Q45 – Water flows through a fire hose of diameter 6.35cm at a rate of . the fire hose ends in a nozzle of inner diameter 2.20cm. What is the speed with which the water exits the nozzle?
3.5 Safety and high pressure · read p. 107