exam questions 2008

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Data provided:None

DEPARTMENT OF MECHANICAL ENGINEERING - Spring Semester 2007-2008

FUNDAMENTAL BIOMECHANICS 1 hour

Multiple choice questions:

Please answer all questions. There could be more than one correctanswer for each question. To obtain maximum marks, you should choose allthe correct answers or write none if none is the correct answer. The exampaper must be returnedwith your answer sheets. Each question carries5 marks (total marks = 100).


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RCtRC

t

RCt epdeQC

etp/

0

/

0

/)(

1)(

5) Human veins normally contain about what proportion of thetotal volume of blood in the systemic vascular system:

A) 90%

B) 80%

C) 70%

D) 60%

E) 50%

6) In the Windkessel model, the following equation holds:

where Q is the inflow from the left ventricle, p is the pressureinside the chamber, R is the resistance, and C is thecompliance. This equation can be solved to give:

A)

B) RCtRCt

RCtepdeQ

Cetp

/

0

/

0

/)(

1)(

C) RCtRCt

epdeQC

tp/

0

/

0

)(1

)(

D) 0/

0

/)(

1)( pdeQ

Cetp

RC

t

RCt

where p0 is the pressure at t=0

7) Compared with arteries, the most important feature of thesystemic veins is:

A) their negative transmural pressure

B) their self-excited oscillation

C) their buckled cross-section

D) their compliance

R

p

dt

dpCQ


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8) The typical Reynolds number range of blood flow in thebody could vary from 1 in small arterioles to approximately4000 in the aorta. It means that compared to arterioles:

A) inertial forces and viscous forces are equally importantin the aorta

B) inertial forces are more important than viscous forcesin the aorta

C) inertial forces are less important than viscous forces inthe aorta

D) inertial forces are dominant in small arterioles

9) Under certain assumptions, we can derive an analytical(Womersley) solution for flow in elastic tubes. The followingis one of the assumptions:

A) the fluid is non-viscous

B) the wall deformation is significant

C) the system is non-linear

D) the velocity profile is uniform

E) the wave length is long compared to the tube

deformation

10) There are several physically observed sources contributingto drag of flying birds. These may include:

A) downwash

B) free surface waves

C) detachment of the boundary layer from the bird body

D) skin friction

11) As people get older, the structure of their arteries maychange. The most important change is:

A) the softening of arterial walls

B) the stiffening of arterial walls

C) the increased lumen sizes

D) the thinning of arterial walls


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12) It is found that a 1% change in radius of a vessel will cause

a 4% change in blood flow rate, provided that:

A) the pressure drop along the vessel is constant

B) the length of the vessel is constant

C) the viscosity of the blood is constant

D) the vessel behaves like a straight and rigid circular cylindricaltube

13) Drag acting on a bird body is composed of pressure drag due to anormal force or pressure on the body surface, caused by:

A) the viscous flow at very low speed

B) flow separation

C) induced drag

D) accompanying shock waves

14) If the work done by air on a birds wing is:

fhLW

00

where0

L is the amplitude of the oscillating lift,

0h is the amplitude of

downward velocity, and is the phase difference between the lift and thedownward velocity. The flutter of the wing will be sustained if:

A)

22

B) 0f

C) 0f

D) 0f


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15) A simply supported column subject to an end thrust can lose itsstability. The critical load when the column first buckles is given by:

A)3

3

R

EI

B) 1,2

22

nL

EIn

C) 32

3

14 R

Eh

D)

L

L

dxdx

dw

dxdx

wdEI

0

2

0

2

2

where R is the radius of the column, Eis the Youngs modulus, isthe Poissons ratio, L is the length of the column, w is thedisplacement, and I is the moment of inertia of the cross-sectionalarea.

16) Under dynamic conditions, three cases may occur in asegment of a collapsible tube:

(i) 0p at entry, 0p at exit;

(ii) 0p at entry, 0p at exit;

(iii) 0p at entry, 0p at exit;

where p is the transmural pressure ei pp . Self excitedoscillations may occur in:

A) Case i,

B) Case ii,

C) Case iii,

D) Any of the cases i, ii and iii


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17) Assuming the frictional loss is negligible and that the tubecross-sectional area depends solely on the transmural pressure, theoccurrence of flow limitation in collapsible tubes may be explained as aresult of the following:

A) the velocity of the flow is greater than the phase velocity ofpropagation of small perturbations

B) the pressure drop is not large enough

C) the upstream transmural pressure becomes negative

D) the flow is turbulent.

18) Which of the following diagrams is known as the StarlingResistor?:

Figure Q18: A, B, C and D

A) B) C)

D)


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19) The figure below shows that the best performers in terms of cost oftransport are:

A) cyclists followed by airplanes, fish, swimmers and birds

B) fish followed by flyers, runners, walkers and manmadevehicles

C) airplanes followed by birds, walkers, runners and man-madevehicles

D) cyclists followed by fish, swimmers, airplanes, walkers andrunners

Figure Q19

20) Downwash of wing is caused by:

A) the Kutta condition

B) the compressibility effects

C) the finite span of a wing

D) the skin friction

END OF QUESTION PAPER

exam questions 2008

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