Question 1

Imagine that you have been given the job of designing a fountain to be the centrepiece of a new shopping mall on the Gold Coast. The fountain will consist of a single upward jet of water, launched from a pipe of radius 2 mm and length 1.2 m. The pipe is fed by recycled water, pushed by a pump which produces a pressure difference of 50 000 Pa. How high will the water in the fountain go? The viscosity of water is 0.001 Pa s, and g = 9.8 m s-2.

Accepted Answer

A)  1.3 m. 
B)  5 m. 
C)  11 m. 
D)  22 m. 
E)  44 m.ANS

Question 2

The water supply to an old suburb in Perth is no longer adequate, and the water company is planning to put in a higher capacity supply. Which of the following options would give the biggest increase in the water flow into the suburb?

Accepted Answer

A)  Re-route the water supply pipeline to a new route that is 13% shorter. 
B)  Dig up the water supply pipeline and replace it with one that has a 10% larger diameter. 
C)  Replace the pumps with ones that provide a 15% larger pressure difference. 
D)  Replace the buried water supply pipeline with one that is on the surface and hence exposed to the sun. The heat from the sun will warm the water and hence reduce its viscosity by around 7%. 
E)  All the other solutions will have the same results.ANS

Question 3

You have been asked to modify the nozzle of a rocket engine. The existing rocket produces a laminar flow of exhaust gasses, but is not powerful enough to lift a new generation of communication satellites. You have been asked to advise on the best way to increase the thrust without causing the flow to become turbulent. The rocket thrust is proportional to the density of the exhaust, to its velocity, and to the square of the nozzle diameter. What is the best approach?

Accepted Answer

A)  Increase the diameter of the nozzle and decrease the velocity by the same factor. 
B)  Increase the density of the exhaust and decrease the velocity by the same factor. 
C)  Increase the velocity of the exhaust and decrease the diameter of the nozzle by the same factor. 
D)  All the other proposed solutions are feasible. 
E)  None of the other proposed solutions are feasible.ANS

Question 4

What is the net force inward acting on a spherical bathysphere of diameter 2.00 m at an ocean depth of 1000 m? (The pressure inside the bathysphere is, hopefully, 1 ATM.) $\rho$(sea water) = 1.02 *103 kg/m3.

Accepted Answer

A) 1.26 * 104 N 
B) 1.26 * 106 N 
C) 1.26 * 108 N 
D) 1.26* 1010 N 
E) 1.26 * 102 N

Question 5

A sphere of radius 1 cm is moving through a vat of corn syrup, which has a viscosity of 1.4 Pa s. A force of 0.01 N is needed to keep it moving at a constant speed. What is the speed? You may assume that Stokes' law applies.

Accepted Answer

A)  3.8 cm s-1. 
B)  26 cm s-1. 
C)  23 cm s-1. 
D)  12 cm s-1. 
E)  6.8 cm s-1.ANS

Question 6

Air within the funnel of a large tornado may have a pressure of only 0.2 ATM. What is the approximate outward force on a (5 m * 10 m) wall if a tornado suddenly envelops the house? (1 ATM = 1.01*105 N/m2.)

Accepted Answer

A) 4 * 103 N 
B) 4 * 104 N 
C) 4 * 105 N 
D) 4 * 106 N 
E) 7*105 N

Question 7

A Boeing 737 airliner has a mass of 20 000 kg and the total area of both wings (top or bottom) is 100 m2. What is the pressure difference between the top and bottom surface of each wing when the airplane is in flight at a constant altitude?

Accepted Answer

A) 1 960 N/m2 
B) 3 920 N/m2 
C) 7 840 N/m2 
D) 4 560 N/m2 
E) 3 070 N/m2

Question 8

How much power is theoretically available from a mass flow of 1000 kg/s of water when it falls a vertical distance of 100 metres?

Accepted Answer

A) 980 kW 
B) 98 kW 
C) 4900 W 
D) 980 W 
E) 9600 W

Question 9

A venturi tube may be used as the inlet to an automobile carburettor. If the 2.0-cm diameter pipe narrows to a 1.0-cm diameter, what is the pressure drop in the constricted section for an airflow of 3.0 m/s in the 2.0-cm section? ($\rho$ = 1.2 kg/m3.)

Accepted Answer

A) 70 Pa 
B) 85 Pa 
C) 100 Pa 
D) 120 Pa 
E) 81 Pa

Question 10

A fountain sends water to a height of 100 metres. What must be the pressurisation (above atmospheric) of the water system? 1 ATM = 1.01 *105 N/m2.

Accepted Answer

A) 1.0 ATM 
B) 4.2 ATM 
C) 7.2 ATM 
D) 9.7 ATM 
E) 8.2 ATM

Question 11

An evaporative cooling unit needs to pump 100 litres of air per second through a pipe of radius 10 cm and length 10 m. How much of a pressure difference must be applied to the air to produce this flow rate? The viscosity of air is 1.8x10-5 Pa s.

Accepted Answer

A)  4.6x10-9 Pa 
B)  1.44 Pa 
C)  0.46 Pa 
D)  460 Pa 
E)  0.057 Pa
ANS

Question 12

The water level in a reservoir is maintained at a constant level. What is the exit velocity in an outlet pipe 3.0 m below the water surface?

Accepted Answer

A) 2.4 m/s 
B) 3.0 m/s 
C) 5.4 m/s 
D) 7.7 m/s 
E) 49 m/s

Question 13

A fountain sends a stream of water 20.0 m up into the air. If the base of the stream is 10.0 cm in diameter, what power is required to send the water to this height?

Accepted Answer

The answer of A fountain sends a stream of water...

Question 14

Water is flowing at 4.0 m/s in a circular pipe. If the diameter of the pipe decreases to 1/2 its former value, what is the velocity of the water downstream?

Accepted Answer

A) 1.0 m/s 
B) 2.0 m/s 
C) 8.0 m/s 
D) 16 m/s 
E) 4.0 m/s

Question 15

In a wind tunnel the pressure on the top surface of a model airplane wing is 8.8 *104 N/m and the pressure on the bottom surface is 9.0 * 104 N/m2. If the area of the top and bottom surfaces of each wing is 2.0 m2, what is the total lift on the model airplane?

Accepted Answer

A) 2.0 *103 N 
B) 8.0 * 103 N 
C) 1.6 * 104 N 
D) 3.6 * 104 N 
E) 1.0 * 103 N

Exam 14: Fluid Dynamics

The water supply to an old suburb in Perth is no longer adequate, and the water company is planning to put in a higher capacity supply. Which of the following options would give the biggest increase in the water flow into the suburb?

What is the net force inward acting on a spherical bathysphere of diameter 2.00 m at an ocean depth of 1000 m? (The pressure inside the bathysphere is, hopefully, 1 ATM.) $\rho$ (sea water) = 1.02 *103 kg/m3.

A sphere of radius 1 cm is moving through a vat of corn syrup, which has a viscosity of 1.4 Pa s. A force of 0.01 N is needed to keep it moving at a constant speed. What is the speed? You may assume that Stokes' law applies.

Air within the funnel of a large tornado may have a pressure of only 0.2 ATM. What is the approximate outward force on a (5 m * 10 m) wall if a tornado suddenly envelops the house? (1 ATM = 1.01*105 N/m².)

A Boeing 737 airliner has a mass of 20 000 kg and the total area of both wings (top or bottom) is 100 m². What is the pressure difference between the top and bottom surface of each wing when the airplane is in flight at a constant altitude?

How much power is theoretically available from a mass flow of 1000 kg/s of water when it falls a vertical distance of 100 metres?

A venturi tube may be used as the inlet to an automobile carburettor. If the 2.0-cm diameter pipe narrows to a 1.0-cm diameter, what is the pressure drop in the constricted section for an airflow of 3.0 m/s in the 2.0-cm section? ( $\rho$ = 1.2 kg/m3.)

A fountain sends water to a height of 100 metres. What must be the pressurisation (above atmospheric) of the water system? 1 ATM = 1.01 *105 N/m².

An evaporative cooling unit needs to pump 100 litres of air per second through a pipe of radius 10 cm and length 10 m. How much of a pressure difference must be applied to the air to produce this flow rate? The viscosity of air is 1.8x10-5 Pa s.

The water level in a reservoir is maintained at a constant level. What is the exit velocity in an outlet pipe 3.0 m below the water surface?

A fountain sends a stream of water 20.0 m up into the air. If the base of the stream is 10.0 cm in diameter, what power is required to send the water to this height?

Water is flowing at 4.0 m/s in a circular pipe. If the diameter of the pipe decreases to 1/2 its former value, what is the velocity of the water downstream?

In a wind tunnel the pressure on the top surface of a model airplane wing is 8.8 104 N/m and the pressure on the bottom surface is 9.0 104 N/m². If the area of the top and bottom surfaces of each wing is 2.0 m², what is the total lift on the model airplane?

Exam 14: Fluid Dynamics

The water supply to an old suburb in Perth is no longer adequate, and the water company is planning to put in a higher capacity supply. Which of the following options would give the biggest increase in the water flow into the suburb?

What is the net force inward acting on a spherical bathysphere of diameter 2.00 m at an ocean depth of 1000 m? (The pressure inside the bathysphere is, hopefully, 1 ATM.) ρ\rhoρ (sea water) = 1.02 *103 kg/m3.

A sphere of radius 1 cm is moving through a vat of corn syrup, which has a viscosity of 1.4 Pa s. A force of 0.01 N is needed to keep it moving at a constant speed. What is the speed? You may assume that Stokes' law applies.

Air within the funnel of a large tornado may have a pressure of only 0.2 ATM. What is the approximate outward force on a (5 m * 10 m) wall if a tornado suddenly envelops the house? (1 ATM = 1.01*105 N/m2.)

A Boeing 737 airliner has a mass of 20 000 kg and the total area of both wings (top or bottom) is 100 m2. What is the pressure difference between the top and bottom surface of each wing when the airplane is in flight at a constant altitude?

How much power is theoretically available from a mass flow of 1000 kg/s of water when it falls a vertical distance of 100 metres?

A venturi tube may be used as the inlet to an automobile carburettor. If the 2.0-cm diameter pipe narrows to a 1.0-cm diameter, what is the pressure drop in the constricted section for an airflow of 3.0 m/s in the 2.0-cm section? ( ρ\rhoρ = 1.2 kg/m3.)

A fountain sends water to a height of 100 metres. What must be the pressurisation (above atmospheric) of the water system? 1 ATM = 1.01 *105 N/m2.

An evaporative cooling unit needs to pump 100 litres of air per second through a pipe of radius 10 cm and length 10 m. How much of a pressure difference must be applied to the air to produce this flow rate? The viscosity of air is 1.8x10-5 Pa s.

The water level in a reservoir is maintained at a constant level. What is the exit velocity in an outlet pipe 3.0 m below the water surface?

A fountain sends a stream of water 20.0 m up into the air. If the base of the stream is 10.0 cm in diameter, what power is required to send the water to this height?

Water is flowing at 4.0 m/s in a circular pipe. If the diameter of the pipe decreases to 1/2 its former value, what is the velocity of the water downstream?

In a wind tunnel the pressure on the top surface of a model airplane wing is 8.8 *104 N/m and the pressure on the bottom surface is 9.0 * 104 N/m2. If the area of the top and bottom surfaces of each wing is 2.0 m2, what is the total lift on the model airplane?

What is the net force inward acting on a spherical bathysphere of diameter 2.00 m at an ocean depth of 1000 m? (The pressure inside the bathysphere is, hopefully, 1 ATM.) $\rho$ (sea water) = 1.02 *103 kg/m3.

Air within the funnel of a large tornado may have a pressure of only 0.2 ATM. What is the approximate outward force on a (5 m * 10 m) wall if a tornado suddenly envelops the house? (1 ATM = 1.01*105 N/m².)

A Boeing 737 airliner has a mass of 20 000 kg and the total area of both wings (top or bottom) is 100 m². What is the pressure difference between the top and bottom surface of each wing when the airplane is in flight at a constant altitude?

A venturi tube may be used as the inlet to an automobile carburettor. If the 2.0-cm diameter pipe narrows to a 1.0-cm diameter, what is the pressure drop in the constricted section for an airflow of 3.0 m/s in the 2.0-cm section? ( $\rho$ = 1.2 kg/m3.)

A fountain sends water to a height of 100 metres. What must be the pressurisation (above atmospheric) of the water system? 1 ATM = 1.01 *105 N/m².

In a wind tunnel the pressure on the top surface of a model airplane wing is 8.8 104 N/m and the pressure on the bottom surface is 9.0 104 N/m². If the area of the top and bottom surfaces of each wing is 2.0 m², what is the total lift on the model airplane?