Thermodynamics and Marks
HERIOT WATT UNIVERSITY
SCHOOL OF ENGINEERING AND PHYSICAL SCIENCES
DEGREE OF BENG IN MECHANICAL ENGINEERING
First Year
Mechanical Engineering Science 3
??day ?? June 2007 ??:?? – ??:??
Answer TWO questions from each section A & B.
Section A
Q1. a) For a Newtonian fluid state an expression for the shear stress.
[4 marks]
b) An ice hockey puck traverses the ice on a thin sheet of water. A puck struck by an ice hockey player Initially travels at a speed of 20 m/sec, the thin layer of water between the puck and the ice has a thickness of 0.2 mm calculate the shear stress if the viscosity of the water is 0.0018 kg/m sec.
[8 marks]
A puck has an approximate diameter of 80 mm, calculate the initial drag force on the puck.
[5 marks]
c) In the figures below the viscosity as a function of temperature is graphed for two fluids, Fluid A and Fluid B; given no other information, identify which fluid is a liquid and which is a gas. Justify your answer.
Fluid A Fluid B
[pic]
[pic]
Figure Q1
[8 marks]
.
Q2. Figure Q2a shows a mercury manometer, (mercury s.g.=13.6) connected to a pipeline transporting oil (oil s.g.=0.85), the other arm of the manometer is exposed to the atmosphere. What is the absolute pressure in the pipeline?
[pic]
Figure Q2a
[10 marks]
Another mercury manometer is connected to two oil pipelines (oil s.g.=0.85) labelled A and B, as shown below in Figure Q2b. Calculate the pressure difference pB-pA.
[pic]
Figure Q2b
[10 marks]
Suppose a pressure gauge was fitted to pipeline A and it measured a pressure of 2 bar. What would the absolute pressure in pipeline B be? Give your answer in bar.
[5 marks]
Q3. a) A hot air balloon has a volume of 1,000 m3(1 thousand m3). Taking the surrounding air density to be 1.21 kg/m3 calculate the buoyancy force.
[5
SCHOOL OF ENGINEERING AND PHYSICAL SCIENCES
DEGREE OF BENG IN MECHANICAL ENGINEERING
First Year
Mechanical Engineering Science 3
??day ?? June 2007 ??:?? – ??:??
Answer TWO questions from each section A & B.
Section A
Q1. a) For a Newtonian fluid state an expression for the shear stress.
[4 marks]
b) An ice hockey puck traverses the ice on a thin sheet of water. A puck struck by an ice hockey player Initially travels at a speed of 20 m/sec, the thin layer of water between the puck and the ice has a thickness of 0.2 mm calculate the shear stress if the viscosity of the water is 0.0018 kg/m sec.
[8 marks]
A puck has an approximate diameter of 80 mm, calculate the initial drag force on the puck.
[5 marks]
c) In the figures below the viscosity as a function of temperature is graphed for two fluids, Fluid A and Fluid B; given no other information, identify which fluid is a liquid and which is a gas. Justify your answer.
Fluid A Fluid B
[pic]
[pic]
Figure Q1
[8 marks]
.
Q2. Figure Q2a shows a mercury manometer, (mercury s.g.=13.6) connected to a pipeline transporting oil (oil s.g.=0.85), the other arm of the manometer is exposed to the atmosphere. What is the absolute pressure in the pipeline?
[pic]
Figure Q2a
[10 marks]
Another mercury manometer is connected to two oil pipelines (oil s.g.=0.85) labelled A and B, as shown below in Figure Q2b. Calculate the pressure difference pB-pA.
[pic]
Figure Q2b
[10 marks]
Suppose a pressure gauge was fitted to pipeline A and it measured a pressure of 2 bar. What would the absolute pressure in pipeline B be? Give your answer in bar.
[5 marks]
Q3. a) A hot air balloon has a volume of 1,000 m3(1 thousand m3). Taking the surrounding air density to be 1.21 kg/m3 calculate the buoyancy force.
[5