webscte.org JEXPO Joint Entrance Exam for Polytechnic – 2020 Model Question Paper : West Bengal State Council of Technical Education

Organisation : West Bengal State Council of Technical Education
Exam: Joint Entrance Exam for Polytechnic – JEXPO-2020
Document Type : Question Paper
Date of Examination : 26th April, 2020
Website : http://webscte.org/jexpo.html

WEBSCTE JEXPO Model Question Paper

Download Question Paper of Joint Entrance Exam for Polytechnic – JEXPO-2020 Sample Question is now available in the official website of West Bengal State Council of Technical Education.

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Mechanics Of Structure

Chapter – I

I. Descriptive type questions :
1. Explain the terms volumetric strain and bulk modulus.
2. Prove that volumetric strain is equal to sum of the strain in three mutually perpendicular direction by taking the examples of (a) bar of rectangular cross-section; (b) bar of circular cross-section.
3. Prove that, if algebraic sum of stresses acting on a body in three mutually perpendicular directions is zero, there will not be any volumetric change in the material.
4. Define Poisson’s ratio, Modulus of Elasticity, Modulus of Rigidity and Bulk Modulus.

5. Derive the relationship between
(a) Modulus of Elasticity and Modulus Rigidity.
(b) Modulus of Elasticity and Bulk Modulus.

6. In a biaxial stress system subject to the direct stresses px and py, and sheer stress ‘q’ determine the normal and tangential stresses on a plane at anti-clockwise angle ? to the plane of px -stresses.
7. Define the terms principal planes and principal stresses. If normal and tangential stresses on a plane at ? to the plane of px forces are

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II. Fill in the blanks type questions :
1. The ratio of change in volume to the original volume is known as ___________.
2. The ratio of identical stress p acting on a body in all direction to the volumetric strain is known as ___________.
3. If a bar is subjected to uni-axial stress ‘p’ volumetric strain will be ___________.
4. If a body is subjected to stresses px, pv and pz the volumetric strain in terms of Poisson’s ratio µ and modulus of elasticity E is given by ___________.
5. The relationship between modulus of elasticity and modulus of rigidity in terms of Poisson’s ratio is ___________.
6. The relationship between modulus of elasticity and bulk modulus in terms of Poisson’s ratio is ___________.
7. The relationship among the three moduli of material in terms excluding Poisson’s ratio is ___________.
8. In case of uni-axial stress, shear stress is maximum at _______ to the axis.
9. The principal plane is the one on which shearing stress is __________.
10. If maximum principal stress is 40 N/mm2 and the minimum is 10 N/mm2, maximum shearing stress is _____________.
11. If a material is subjected to general biaxial stress system of px, py and q, the centre of Mohr’s circle is _____________.
12. The radius of Mohr’s circle is given by _____________. .
13. The direction of principal plane ? in a two dimensional stress system is given by _____________.
14. The direction of maximum shear stress makes angle _____________ to the direction of principal planes.

Chapter – II

I. Descriptive Type Questions
1. Draw shear force and bending moment diagrams for a typical cantilever subject to uniformly varying load from zero at free end to w/unit length at fixed support.
2. Draw shear force and bending moment diagram for a typical simply supported beam subjected to uniformly varying load of intensity zero at support A to w/unit length at support B.
3. Draw shear force and bending moment diagram for a typical simply supported beam subject to a clockwise moment M0 at a point, distance ‘a’ from support A.

II. Fill in the blank type questions
1. In a cantilever of span L subjected to uniformly varying load of intensity zero at free end and w/unit length at fixed end, maximum shear force is __________.
2. In the above case, maximum moment is __________.
3. In a simply supported beam of span L subjected to uniformly varying load of intensity zero at end A to w/unit length at the end B, shear force at A is __________.
4. In the above case shear force varies __________.
5. In the above case maximum moment occurs at _________ from end A.
6. In a simply supported beam of span L subjected to external moment couple M0 at distance ‘a’ from support A, shear force at any point is equal to __________.
7. In the above case, bending moment just to the left of the section at distance ‘a’ is __________ and just to the right of the section is __________.

III. State whether the following statements are true or false
1 . If a load varies uniformly, bending moment under it varies parabolically.
2. In cantilever of span /, lubjlit In uniformly distributed load, maximum moment occurs at fixed support and its value is
3. The shear force is constant in a simply supported beam subjected to external couple moment.
4. The difference between moments just to the left and just to the right of a section where external moment M0 is acting is M0.

Chapter – III

1. A steel plate of width 60 mm and of thickness 10 mm is bent into a circular arc of radius 10 m. Determine the maximum stress induced and the bending moment which will produce the maxi¬mum stress. Take E = 2 ? 105 N/mm2. [Ans. 100 N/mm2 ; 100 N-m.]
2. A cast iron pipe of external diameter 60 mm, internal diameter of 40 mm, and of length 5 m is supported at its ends. Calculate the maximum bending stress induced in the pipe if it carries a point load of 100 N at its centre. [Ans. 7.34 N/mm2]
3. A rectangular beam 300 mm deep is simply supported over a span of 4 m. What uniformly distributed load per metre, the beam may carry if the bending stress is not to exceed 120 N/mm2? Take I = 8 ? 106 mm4. [Ans. 3.2 kN/m]
4. A cast iron cantilever of length 1.5 metre fails when a point load W is applied at the free end. If the section of the beam is 40 mm ? 60 mm and the stress at the failure is 120 N/mm2, find the point load applied. [Ans. 1.92 kN]
5. A cast iron beam 20 mm ? 20 mm in section and 100 cm long is simply supported at the ends. It carries a point load W at the centre. The maximum stress induced is 120 N/mm2. What uniformly distributed load will break a cantilever of the same material 50 mm wide, 100 mm deep and 2 m long ? [Ans. 5 kN per m run]

I. Descriptive type questions :
1. Write down the assumptions made in the theory of simple bending.
2. Deduce the equation with their usual notations.
3. What do you mean by neutral plane and neutral axis of a beam?
4. What is flexural strength of a beam section?
5. Write down the factors on which the flexural strength of a section depends.
6. Explain what moment of resistance is.
7. What do you mean by section modulus of a section?
8. Explain the difference between Pure Bending & Ordinary Bending.
9. Give the expression for finding shearing stress in a beam. Explain each term used.

II. Fill in the blanks type questions :
1. In a simply supported beam, the maximum compressive bending stress will develop at the ______ fibre.
2. A cantilever carries an uniformly distributed load throughout, the nature of bending stress at the bottom most layer will be ________.
3. If the cross-section of a beam is symmetrical about the neutral axis the magnitude of the stress at the top most and bottom most layer will be ________.
4. The strength of a beam depends on __________.
5. In a cantilever beam, the maximum compressive stress will develop at the ______ most layer of the loaded beam.
6. The bending stress in a beam is directly proportional to ____________.
7. The bending stress in a beam is ________ proportional to bending moment.
8. In a simply supported beam, the maximum tensile stress will occur at the _____________.
9. The magnitude of the bending stress at any layer is ________ proportional to the distance of the layer from the neutral axis.
10. The magnitude of bending stress is ________proportional to the moment of inertia of the cross-section of the beam about neutral axis.

III. State whether the following statement are true or false :
1. The radius of gyration of an area is the square root of the moment of inertia divided by area.
2. The unit of section modulus and area are same.
3. The stress intensity in any fibre is inversely proportional to the distance of the fibre from the neutral axis.
4. The bending stress developed at neutral axis is maximum tensile in nature.
5. The section modulus of a circular section of diameter‘d’ is .
6. Neutral axis of a beam in the axis at which SF is zero.
7. Bending stress is zero at neutral axis.
8. The strength of the beam mainly depends on bending moment.
9. The intensity of bending stress of any point in a beam varies directly with the distance of point from the neutral axis.
10. The shear force in a beam is zero under pure bending case.