## 02.5. fluid dynamics

Question Number. 1. The specific gravity of a substance is calculated by.

Option A. density of the body squared multiplied by the density of water.

Option B. the density of the body divided by the density of water.

Option C. density of the body multiplied by the density of water.

Correct Answer is. the density of the body divided by the density of water.

Explanation. Specific' always means 'per' something or divide by.

Question Number. 2. The SI unit of density is the.

Option A. kilogram per cubic metre (kg/m3).

Option B. Pascal (Pa).

Option C. cubic metre (m3).

Correct Answer is. kilogram per cubic metre (kg/m3).

Explanation. NIL.

Question Number. 3. Relative density is.

Option A. density of water x density of medium.

Option B. density of water/density of medium.

Option C. density of medium/density of water.

Correct Answer is. density of medium/density of water.

Explanation. NIL.

Question Number. 4. The standard for measuring density is.

Option A. 0 °C and 760 mm of mercury.

Option B. -20 °C and 700 mm of mercury.

Option C. +20 °C and 760 mm of mercury.

Correct Answer is. 0 °C and 760 mm of mercury.

Explanation. STP.

Question Number. 5. 1kg of water is heated from 0 °C to 2 °C. Its volume will.

Option A. decrease.

Option B. stay the same.

Option C. increase.

Correct Answer is. decrease.

Explanation. When ice melts, its volume decreases up to 3 °C.

Question Number. 6. A pilot requests 9.2 tonnes of fuel. The bowser driver reports to the pilot that the specific gravity is 0.8, what will the uplift be?.

Option A. 7360 litres.

Option B. 11500 litres.

Option C. 9200 litres.

Correct Answer is. 11500 litres.

Explanation. 1 litre of water has a mass of 1kg. 1000 litres of water has a mass of 1 metric tonne. 9.2 tonnes of water is 9200 litres. But fuel is lighter than water (0.8x) so the uplift will be more than 9200 litres.

Question Number. 7. Specific gravity.

Option A. is measured in kg/m2.

Option B. is measured in kg/m3.

Option C. has no units.

Correct Answer is. has no units.

Explanation. Specific gravity is the density of the fluid divided by the density of water. Since both have the same units (kg/m3) they cancel - hence, no units.

Question Number. 8. The standard temperature and pressure for measuring the density of liquids is.

Option A. 15 °C and 760 mmHg.

Option B. 0 °C and 760 mmHg.

Option C. 4 °C and 760 mmHg.

Correct Answer is. 4 °C and 760 mmHg.

Explanation. Since water is most dense at 4 °C (1000 kg/m3), this is used as the standard temperature. When working out specific gravity, the fluid in question must also be 4 °C. (But remember it is 0 °C for gases, and room temp - 20 °C - for barometers).

Question Number. 9. The standard temperature and pressure for measuring the volume of liquids and solids is.

Option A. 20 °C and 700 mmHg.

Option B. 20 °C and 760 mmHg.

Option C. 0 °C and 760 mmHg.

Correct Answer is. 20 °C and 760 mmHg.

Explanation. Since the volume of solids and gases changes with temperature (and a lesser amount with pressure) the standard for measuring volume is 20 °C. (room temp.) and 760mmHg (standard sea level atmospheric pressure).

Question Number. 10. Given that 1 cubic foot of water weighs 62.4 lbs and the specific gravity of fuel is 0.81, what is the weight of 10 cubic foot of fuel?.

Option A. 402.8 lbs.

Option B. 505.4 lbs.

Option C. 770.3 lbs.

Correct Answer is. 505.4 lbs.

Explanation. 10 * 62.4 = 624. 624 * 081 =.

Question Number. 11. At what temperature does water have the greatest density?.

Option A. 0 °C.

Option B. 100 °C.

Option C. 4 °C.

Correct Answer is. 4 °C.

Explanation. Solidification begins at 4 °C when cooling.

Question Number. 12. The specific gravity of methylated spirit is 0.8. Its density is.

Option A. 800 g/m3.

Option B. 800 kg/m3.

Option C. 80 kg/m3.

Correct Answer is. 800 kg/m3.

Explanation. sg = density of fluid/density of water density of fluid = sg * density of water density of water = 1000 kg/m3.

Question Number. 13. The density of Cu is 8,900kg/m3. What is its relative density?.

Option A. 890.

Option B. 8.9.

Option C. 89.

Correct Answer is. 8.9.

Explanation. rel. density = density of substance/density of water= 8900/1000.

Question Number. 14. Atmospheric pressure at ISA conditions is.

Option A. 1013 pa.

Option B. 1013 bar.

Option C. 1013 mBar.

Correct Answer is. 1013 mBar.

Explanation. NIL.

Question Number. 15. Convert 220 gallons to litres.

Option A. 1000 litres.

Option B. 48.4 litres.

Option C. 500 litres.

Correct Answer is. 1000 litres.

Explanation. Imagine how many times a large coke bottle goes into a normal engine oil container (about 4 (and a bit)), then * 220. http://www.metric-conversions.org/

Question Number. 16. The SI unit of pressure is the.

Option A. Newton per metre squared (N/m2).

Option B. Cubic metre (m3).

Option C. kilogram per metre cubed (kg/m3).

Correct Answer is. Newton per metre squared (N/m2).

Explanation. Pressure = force / area. So units of pressure is Newtons / square metre (or better known as Pascals).

Question Number. 17. A gauge indicates 15 PSIG. What is the absolute pressure?.

Option A. 30 PSI.

Option B. 0.3 PSI.

Option C. Zero PSI.

Correct Answer is. 30 PSI.

Explanation. Absolute pressure = gauge pressure + atmospheric pressure. (The G in PSIG means 'gauge') Atmospheric pressure varies slightly so is not always the 14.7 PSI of the ISA. http://en.wikipedia.org/wiki/Pound-force_per_square_inch

Question Number. 18. Water is most dense at.

Option A. -4 °C.

Option B. 0 °C.

Option C. +4 °C.

Correct Answer is. +4 °C.

Explanation. As water cools, the molecules begin to crystallise at 4 °C. Crystallized water (i.e. ice) has a greater volume than liquid water and therefore less density (that is why ice floats). http://www.physicalgeography.net/fundamentals/8a.html

Question Number. 19. Viscosity can be described as.

Option A. Newton's 1st law of motion.

Option B. fluids flowing in a straight line.

Option C. the internal resistance for a fluid to flow.

Correct Answer is. the internal resistance for a fluid to flow.

Explanation. Viscosity is opposition to flow of a fluid.

Question Number. 20. How much lift is produced on a wing can be derived from.

Option A. Bernoulli's Theorem.

Option B. Faraday's law.

Option C. Charles law.

Correct Answer is. Bernoulli's Theorem.

Explanation. Bernoulli's theorem.

Question Number. 21. Pressure in a pipe is.

Option A. force per unit area.

Option B. mass divided by cross-sectional area.

Option C. weight per unit area.

Correct Answer is. force per unit area.

Explanation. NIL.

Option A. density of the body squared multiplied by the density of water.

Option B. the density of the body divided by the density of water.

Option C. density of the body multiplied by the density of water.

Correct Answer is. the density of the body divided by the density of water.

Explanation. Specific' always means 'per' something or divide by.

Question Number. 2. The SI unit of density is the.

Option A. kilogram per cubic metre (kg/m3).

Option B. Pascal (Pa).

Option C. cubic metre (m3).

Correct Answer is. kilogram per cubic metre (kg/m3).

Explanation. NIL.

Question Number. 3. Relative density is.

Option A. density of water x density of medium.

Option B. density of water/density of medium.

Option C. density of medium/density of water.

Correct Answer is. density of medium/density of water.

Explanation. NIL.

Question Number. 4. The standard for measuring density is.

Option A. 0 °C and 760 mm of mercury.

Option B. -20 °C and 700 mm of mercury.

Option C. +20 °C and 760 mm of mercury.

Correct Answer is. 0 °C and 760 mm of mercury.

Explanation. STP.

Question Number. 5. 1kg of water is heated from 0 °C to 2 °C. Its volume will.

Option A. decrease.

Option B. stay the same.

Option C. increase.

Correct Answer is. decrease.

Explanation. When ice melts, its volume decreases up to 3 °C.

Question Number. 6. A pilot requests 9.2 tonnes of fuel. The bowser driver reports to the pilot that the specific gravity is 0.8, what will the uplift be?.

Option A. 7360 litres.

Option B. 11500 litres.

Option C. 9200 litres.

Correct Answer is. 11500 litres.

Explanation. 1 litre of water has a mass of 1kg. 1000 litres of water has a mass of 1 metric tonne. 9.2 tonnes of water is 9200 litres. But fuel is lighter than water (0.8x) so the uplift will be more than 9200 litres.

Question Number. 7. Specific gravity.

Option A. is measured in kg/m2.

Option B. is measured in kg/m3.

Option C. has no units.

Correct Answer is. has no units.

Explanation. Specific gravity is the density of the fluid divided by the density of water. Since both have the same units (kg/m3) they cancel - hence, no units.

Question Number. 8. The standard temperature and pressure for measuring the density of liquids is.

Option A. 15 °C and 760 mmHg.

Option B. 0 °C and 760 mmHg.

Option C. 4 °C and 760 mmHg.

Correct Answer is. 4 °C and 760 mmHg.

Explanation. Since water is most dense at 4 °C (1000 kg/m3), this is used as the standard temperature. When working out specific gravity, the fluid in question must also be 4 °C. (But remember it is 0 °C for gases, and room temp - 20 °C - for barometers).

Question Number. 9. The standard temperature and pressure for measuring the volume of liquids and solids is.

Option A. 20 °C and 700 mmHg.

Option B. 20 °C and 760 mmHg.

Option C. 0 °C and 760 mmHg.

Correct Answer is. 20 °C and 760 mmHg.

Explanation. Since the volume of solids and gases changes with temperature (and a lesser amount with pressure) the standard for measuring volume is 20 °C. (room temp.) and 760mmHg (standard sea level atmospheric pressure).

Question Number. 10. Given that 1 cubic foot of water weighs 62.4 lbs and the specific gravity of fuel is 0.81, what is the weight of 10 cubic foot of fuel?.

Option A. 402.8 lbs.

Option B. 505.4 lbs.

Option C. 770.3 lbs.

Correct Answer is. 505.4 lbs.

Explanation. 10 * 62.4 = 624. 624 * 081 =.

Question Number. 11. At what temperature does water have the greatest density?.

Option A. 0 °C.

Option B. 100 °C.

Option C. 4 °C.

Correct Answer is. 4 °C.

Explanation. Solidification begins at 4 °C when cooling.

Question Number. 12. The specific gravity of methylated spirit is 0.8. Its density is.

Option A. 800 g/m3.

Option B. 800 kg/m3.

Option C. 80 kg/m3.

Correct Answer is. 800 kg/m3.

Explanation. sg = density of fluid/density of water density of fluid = sg * density of water density of water = 1000 kg/m3.

Question Number. 13. The density of Cu is 8,900kg/m3. What is its relative density?.

Option A. 890.

Option B. 8.9.

Option C. 89.

Correct Answer is. 8.9.

Explanation. rel. density = density of substance/density of water= 8900/1000.

Question Number. 14. Atmospheric pressure at ISA conditions is.

Option A. 1013 pa.

Option B. 1013 bar.

Option C. 1013 mBar.

Correct Answer is. 1013 mBar.

Explanation. NIL.

Question Number. 15. Convert 220 gallons to litres.

Option A. 1000 litres.

Option B. 48.4 litres.

Option C. 500 litres.

Correct Answer is. 1000 litres.

Explanation. Imagine how many times a large coke bottle goes into a normal engine oil container (about 4 (and a bit)), then * 220. http://www.metric-conversions.org/

Question Number. 16. The SI unit of pressure is the.

Option A. Newton per metre squared (N/m2).

Option B. Cubic metre (m3).

Option C. kilogram per metre cubed (kg/m3).

Correct Answer is. Newton per metre squared (N/m2).

Explanation. Pressure = force / area. So units of pressure is Newtons / square metre (or better known as Pascals).

Question Number. 17. A gauge indicates 15 PSIG. What is the absolute pressure?.

Option A. 30 PSI.

Option B. 0.3 PSI.

Option C. Zero PSI.

Correct Answer is. 30 PSI.

Explanation. Absolute pressure = gauge pressure + atmospheric pressure. (The G in PSIG means 'gauge') Atmospheric pressure varies slightly so is not always the 14.7 PSI of the ISA. http://en.wikipedia.org/wiki/Pound-force_per_square_inch

Question Number. 18. Water is most dense at.

Option A. -4 °C.

Option B. 0 °C.

Option C. +4 °C.

Correct Answer is. +4 °C.

Explanation. As water cools, the molecules begin to crystallise at 4 °C. Crystallized water (i.e. ice) has a greater volume than liquid water and therefore less density (that is why ice floats). http://www.physicalgeography.net/fundamentals/8a.html

Question Number. 19. Viscosity can be described as.

Option A. Newton's 1st law of motion.

Option B. fluids flowing in a straight line.

Option C. the internal resistance for a fluid to flow.

Correct Answer is. the internal resistance for a fluid to flow.

Explanation. Viscosity is opposition to flow of a fluid.

Question Number. 20. How much lift is produced on a wing can be derived from.

Option A. Bernoulli's Theorem.

Option B. Faraday's law.

Option C. Charles law.

Correct Answer is. Bernoulli's Theorem.

Explanation. Bernoulli's theorem.

Question Number. 21. Pressure in a pipe is.

Option A. force per unit area.

Option B. mass divided by cross-sectional area.

Option C. weight per unit area.

Correct Answer is. force per unit area.

Explanation. NIL.