TOTAL MECHANICAL ENGINEERING

Section

Simple Stress and Strain.

Principle Stress, Strain and Strain energy.

Stresses in Beam.

Deflection of beam.

Torsion and Axially Loaded Column.

Simple stress strain

Quiz

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A steel bar of 5 mm is heated from 15° C to 40° C and it is free to expand. The bar will induce
1. no stress
2. shear stress
3. tensile stress
4. compressive stress
When a body is subjected to two equal and opposite pushes, as a result of which the body tends to reduce its length, the stress and strain induced is compressive.
1. True
2. False
The rectangular beam 'A' has length l, width b and depth d. Another beam 'B' has the same length and depth but width is double that of 'A'. The elastic strength of beam 'B' will be as compared to beam A.
1. same
2. double
3. four times
4. six times
the deformation per unit length is called
1. tensile stress
2. compressive stress
3. compressive stress
4. strain
When a bar is cooled to - 5°C, it will develop
1. no stress
2. shear stress
3. shear stress
4. compressive stress
The stress at which the extension of the material takes place more quickly as compared to the increase in load, is called
1. elastic limit
2. yield point
3. ultimate point
4. breaking point
Whenever a material is loaded within elastic limit, stress is strain.
1. equal to
2. directly proportional to
3. inversely proportional to
In the below figure, the stress corresponding to point D is
1. yield point stress
2. breaking stress
3. ultimate stress
4. elastic limit
The Poisson's ratio for cast iron varies from
1. 0.33 to 0.37
2. 0.21 to 0.26
3. 0.31 to 0.34
4. 0.32 to 0.42
The ratio of change in volume to the original volume is called
1. Linear Strain
2. Lateral Strain
3. Volumetric Strain
4. Poisson's Ratio
The ductility of a material with the increase in percentage reduction in area of a specimen under tensile test.
1. increases
2. decreases
3. remains same
The rectangular beam 'A' has length l, width b and depth d. Another beam 'B' has the same length and width but depth is double that of 'A'. The elastic strength of beam B will be as compared to beam A.
1. same
2. double
3. four times
4. six times
percentage reduction in area of a certain specimen made of material 'A' under tensile test is 60% and the percentage reduction in area of a specimen with same dimensions made of material 'B' is 40%, then
1. the material A is more ductile than material B
2. the material B is more ductile than material A
3. the ductility of material A and B is equal
4. the material A is brittle and material B is ductile
The unit of modulus of elasticity is same as those of
1. stress, strain and pressure
2. stress, force and modulus of rigidity
3. strain, force and pressure
4. stress, pressure and modulus of rigidity
bar of length L meters extends by l mm under a tensile force of P. The strain produced in the bar is
1. l/L
2. 0.1 l/L
3. 0.01 l/L
4. 0.001 l/L
A rod is enclosed centrally in a tube and the assembly is tightened by rigid washers. If the assembly is subjected to a compressive load, then
1. rod is under compression
2. tube is under compression
3. both rod and tube are under compression
4. tube is under tension and rod is under compression
When a bar of length l, width b and thickness t is subjected to a pull of P, its
1. length, width and thickness increases
2. length, width and thickness decreases
3. length increases, width and thickness decreases
4. length decreases, width and thickness increases
The ratio of the largest load in a test to the original cross-sectional area of the test piece is called
1. elastic limit
2. yield stress
3. ultimate stress
4. breaking stress
In the below figure, the point E represents the maximum stress.
1. True
2. False
Strain is equal to (where l = Original length, and δl = Change in length)
1. l/δl
2. δl/l
3. l.δl
4. l + δl
Two bars of different materials and same size are subjected to the same tensile force. If the bars have unit elongation in the ratio of 2:5, then the ratio of modulus of elasticity of the two materials will be
1. 2:5
2. 5:2
3. 4:3
4. 3:4
If the modulus of elasticity of a material is twice its modulus of rigidity, then the Poisson's ratio of the material is equal to zero.
1. Correct
2. Incorrect
A beam of uniform strength may be obtained by
1. keeping the width uniform and varying the depth
2. keeping the depth uniform and varying the width
3. varying the width and depth both
4. any one of the above
When a circular bar tapering uniformly from diameter d1, at one end to diameter d2 at the other end, is subjected to an increase in temperature (t), then the thermal stress induced is (where α = Coefficient of linear expansion, and E = Modulus of elasticity for the bar material)
The deformation of the bar per unit length in the direction of the force is known as
1. linear strain
2. lateral strain
3. volumetric strain
4. shear strain
When a bar of length l and diameter d is rigidly fixed at the upper end and hanging freely, then the total elongation produced in the bar due to its own weight is (where w = Weight per unit volume of the bar)
The volumetric strain is the ratio of the
1. original thickness to the change in thickness
2. change in thickness to the original thickness
3. original volume to the change in volume
4. change in volume to the original volume
The thermal or temperature stress is a function of
1. Increase In Temperature
2. Modulus Of Elasticity
3. Coefficient Of Linear Expansion
4. All Of These
Which of the following statement is wrong?
1. The deformation of the bar per unit length in the direction of the force is called linear strain.
2. The Poisson's ratio is the ratio of lateral strain to the linear strain.
3. The ratio of change in volume to the original volume is called volumetric strain.
4. The bulk modulus is the ratio of linear stress to the linear strain.
The ratio of bulk modulus to Young's modulus for a Poisson's ratio of 0.25 will be
1. 1/3
2. 2/3
3. 1
4. 3/2
A bar of copper and steel form a composite system, which is heated to a temperature of 40°C. The stress induced in the copper bar will be
1. tensile
2. compressive
3. shear
4. zero
In the below figure, the point C represents
1. elastic limit
2. upper yield point
3. lower yield point
4. breaking point
. The thermal stress upon the cross-sectional area of the bar.
1. depends
2. does not depend
When a rectangular bar of length l, breadth b and thickness t is subjected to an axial pull of P, then linear strain (ε) is given by (where E = Modulus of elasticity)
The relation between Young's modulus (E) and bulk modulus (K) is given by A.
Young's modulus may be defined as the ratio of
1. inear stress to lateral strain
2. lateral strain to linear strain
3. linear stress to linear strain
4. . shear stress to shear strain
In the below figure, represents glass.
1. curve A
2. curve B
3. curve C
4. curve D
When a bar of length l, width b and thickness t is subjected to a push of P, its
1. length, width and thickness increases
2. length, width and thickness decreases
3. length increases, width and thickness decreases
4. length decreases, width and thickness increases
When a body is subjected to three mutually perpendicular stresses, of equal intensity, the ratio of direct stress to the corresponding volumetric strain is known as
1. Young's modulus
2. modulus of rigidity
3. bulk modulus
4. Poisson's ratio
The ratio of shear modulus to the modulus of elasticity for a Poisson's ratio of 0.4 will be
1. 5/7
2. 7/5
3. 5/14
4. 14/5