ME 273: Solid and Fluid Phenomena

Time : 3 hours                                                                                                    Date:2-5-2005

FINAL EXAM

Total Marks: 100

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20

  1. The pair potential for an hypothetical solid is given by

        with A= 10-77 Jm6  and B = 10-134 Jm12. Calculate

    1. Elastic Modulus of the solid
    2. Equilibrium interatomic distance (r = ro)
    3. Minimum energy distance between two atoms (r = re)
    4. The Maximum adhesive force between two atoms.

 

20

  1. Describe in detail the force experienced by a sphere of material A brought along the Z- axis from infinity  towards a surface, Z=0 of Material B and penetrated to a depth of about half of its radius . Assume half space approximation for B i.e it extends to infinite in ±X, ±Y and –Z directions. What are the issues involve in measuring this force. Explain the working principle of one instrument that is capable of measuring this clearly indicating the range in it is designed to operate.

 

4x10=40

  1. Write short notes on
    1. Atomic processes involved in fracture
    2. Double layer
    3. Adhesion between surfaces and Hamaker’s Constant
    4. Different contributing forces to the Vander Walls forces between atoms and molecules.