1.14. EXERCISES
7.Draw a representative stress-strain diagram of a brittle material.
8.Draw a representative stress-strain diagram of a ductile material.
9.List a set of information about a material that you can extract its stress-strain
diagram.
10.Define Young’s Modulus. What is its unit?
11.Define Rigidity Modulus. What is its unit?
12.Define Bulk Modulus. What is its unit?
13.Define Poisson’s ratio.
14.When a compressed string is dissolved in acid what happens to the elastic
potential energy of the string [ 8 ]?
15.When a wire is repeatedly bent back and forth it becomes hot. Why?
16.When a block of mass is suspended by a long wire of lengthL, the elastic
potential energy stored in the wire is^12 ◊stress◊strain◊volume. Show that
it is equal to^12 Mgl, wherelis the extension. The loss in gravitational potential
energy of mass-earth system isMgl. Where does the remaining^12 Mglgo [ 8 ]?
17.List any two factors which a ect elastic modulus and tensile strength.
18.How do temperature and impurity a ect the elasticity of materials?
19.How do hammering and rolling a ect the elasticity of materials?
20.What is meant by (a) neutral surface and (b) neutral axis of a beam.
21.How are the various filaments of a beam a ected when the beam is loaded?
22.Distingush between uniform bending and non-unifrom bending.
23.What are I- shape girders?
24.State the advantages and limitations of I-shaped girders.Part B (16 marks)- Questions for detailed Answers (25 to 28 minutes to answer each)
1.Derive an expression for the torsional couple per unit angular twist when a
cylinder is twisted.
2.Derive an expression for the period of oscillation of a torsional pendulum. How
can it be used to determine the torsional rigidity (Rigidity Modulus) of a wire?
3.What is meant by bending moment of a beam? Derive the expression for the
bending moment of a beam.
4.Derive the expression for the depression at the free end of a cantilever due
to load. Describe an experiment to determine the young’s modulus of the
cantilever using this expression.
5.Explain, with necessary theory, the method of determination of young’s mod-
ulus of elasticity of the material of the beam supported at its ends and loaded
in the middle (nonunifrom bending).
6.Explain, with necessary theory, the method of determination of young’s mod-
ulus of elasticity of the material of the beam supported symmetrically on two
knife edges and loaded equally at its ends (unifrom bending).