Download Examination Paper: Mechanics 1, Cork Institute of Technology, 2010 and more Exams Mechanics in PDF only on Docsity!
CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2009/
Module Title: Mechanics 1
Module Code: MECH 6029
School: Mechanical & Process Engineering
Programme Title: Bachelor of Engineering (Honours) in Sustainable Energy – Stage 1 Bachelor of Engineering in Building Services Engineering – Stage 1
Programme Code: ESENT_8_Y EBSEN_7_Y
External Examiner(s): Mr. R. Linger, Dr. E. Coyle, Dr. B. Costelloe, Mr. P. O’Sullivan Internal Examiner(s): Mr. W. Corr, Ms. M. Cullinane, Dr. P. Walsh
Instructions: Answer any FOUR questions. All question carry equal marks
Duration: 2 hours
Sitting: Summer 2010
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
Question 1:
(a) What is meant by a Scalar and a Vector? Give one example of each. (5) (b) A bracket firmly attached to the ceiling holds three masses as shown. Assuming the pulleys used are frictionless, use either a graphical or analytical method to find: i. The tension in each of the ropes (4) ii. The reaction force of the ceiling on the bracket (8)
(c) The centre of gravity, G, of a rear-engine car with mass 1.5 Tonne is located as shown in the figure below. Determine the reaction force of the ground on both the front and rear wheels when it is in equilibrium. (8)
Question 2:
(a) Explain what is meant by Potential Energy and Kinetic Energy? (6) (b) A concrete slab of mass 2 Tonne is suspended 10m above the ground by the crane shown. a. Find the potential and kinetic energy of the slab when suspended as shown (6)
(c) At time t=0 seconds, a fault occurs and the steel rope holding the slab snaps. You are required to find: a. The potential and kinetic energy when the slab has fallen to a height of 5m. (6) b. The velocity at which the slab impacts the ground as well as the time taken before impact occurs. (7)
Question 5:
(a) Distinguish between static and kinetic frictions. Which has the higher coefficient of friction for the same pair of materials? (4 marks) (b) Which of the following pairs has high coefficient of friction and which has low: and why is it desired so; explain clearly:
- car tyre on road
- whiteboard marker on whiteboard
- hand on steering wheel
- grit on icy roads (6 marks)
(c) A 20kg package just slides down a 30° inclined ramp of its own accord. Calculate: (i) the coefficient of friction between package and ramp (5 marks) (ii) the pull, parallel to the ramp, to just haul the package up the ramp (10 marks)
Question 6:
(a) Define the terms stress and strain; Give their units and explain why they are used in place of
force and extension. (4 Marks)
(b) Sketch a simple tensile test result for a highly brittle and a highly ductile material.
Give one example of each type of material. (6 Marks)
(c) Define Young’s Modulus, E for a material and explain its physical meaning. (4 Marks)
(d) Figure 6.1 shows a simple tensile test result for an aluminium specimen.
From the graph: (i) Read approximately:
- The yield strength (2 marks)
- The ultimate strength (2 marks) (ii) Calculate Young’s Modulus for the material. (5 marks) (iii) Is this a brittle or a ductile material? Why? (2 marks)
