JNTU
JNTU B.Tech II MECHANICS OF SOLIDS AND MECHANICS OF FLUIDS Previous Question Paper (March - 2021 - R16)
Answer any five questions. All questions carry equal marks.
Main
Explain factor of safety, Shear strain and volumetric strain.
Answer
Factor of Safety: It is defined as the ratio of the ultimate stress of a material to the allowable or working stress. It ensures that the actual load on a component is significantly lower than the load that would cause failure, providing a margin of safety.
Shear Strain: It is the angular deformation produced in a body when subjected to shear stress. It is defined as the change in the right angle between two perpendicular lines originally meeting at a point in the body.
Volumetric Strain: It is the ratio of the change in volume of a body to its original volume when subjected to external forces.
A tie-bar is to carry a maximum load of 15kN and made of mild steel with ultimate tensile strength of 700Mpa. If a factor of safety of 3 is specified, what is the maximum diameter of the bar? Also find the percentage of elongation of the bar at maximum load. Take E = 2.1GPa.
Answer
Given: Load (P) = 15 kN = 15,000 N, Ultimate Stress (σᵤ) = 700 MPa = 700 N/mm², Factor of Safety (FoS) = 3, Young's Modulus (E) = 2.1 GPa = 2100 N/mm².
1. Calculate Allowable Stress (σₐ):
2. Calculate Diameter (d):
3. Percentage of Elongation:
Using Hooke's Law, strain (ε) = σₐ / E.
The percentage of elongation is ε × 100.
A bar of 30mm diameter is subjected to an axial load of 65kN. The extension over a gauge length of 200mm is 0.3 and decrease in diameter is 0.015mm. Calculate:
a) Poisson’s ratio
b) Modulus of elasticity and modular of rigidity.
Answer
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Draw the S.F and B.M diagrams for a cantilever, when the total length is 5m and a point load of 1.5kN is placed at 1m distance from fixed end and 1kN at free end of the beam. A UDL of 2kN/m is spread over 2m length, starting from 2m distance from fixed end.
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A rectangular beam 12cms wide by 24cms deep is subjected to a maximum bending moment of 500kN-m. Determine the maximum stress in the beam. If the value of E for the material is 200GPa, find out the radius of curvature for the portion of beam, where the B.M is maximum.
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A hollow shaft has to transmit 350kW at 100 rpm. If the shear stress in the shaft is not to exceed 65 MN/m2 and internal diameter, find the external and internal diameter of the shaft. Find the internal and external diameters assuming that the maximum torque is 1.5 times the mean torque.
Answer
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Differentiate between compressible and incompressible fluids.
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Determine the total pressure and centre of pressure of a circular plate of diameter 2m which is placed vertically in water in such a way that the centre of circular plate is 3m below the surface of water.
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Explain about surface tension and capillary effects.
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A U-tube manometer is used to measure the pressure of water in a pipe line, which is at higher than the atmospheric pressure. The contact between water and mercury is in the left limb. Determine the pressure of water in the pipe line, if the difference of the level of mercury in the limits of U-tube is 10cms and free surface of mercury in the right limb is at the centre of pipe line.
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How the turbulent and laminar flows are occurred?
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Water is flowing through a pipe of length 150m having diameters 500mm at the upper end 300mm at lower end. The rate of flow of water is 60 liters/sec. The pipe has a slope of 1 in 30. Find the pressure at the lower end, if the pressure at the higher level is 20N/cm2.
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