CHAPTER-1

STRESS

• Q1: Define Force.
  Ans:A force is a push or pull applied on the body. The unit of force is N.
• Q2: Name the types of stress.
  Ans:The types are:

  • ➔ Direct Stress
    • ➔ Tensile Stress
    • ➔ Compressive Stress
  • ➔ Shear Stress
• Q3: Write down the unit of stress in:
  Ans:

  System	Measuring Unit
  MKS	kg/m2
  CGS	g/cm2
  FPS	lbs/ft2
  SI	N/m2

• Q4: Define Axial Force.
  Ans:The force acting at the centroid of an object is called axial force.
• Q5: Define Eccentric Force.
  Ans:The force acting away from the centroid of an object is called eccentric force.
• Q6: Define Stress.
  Ans:The stress produced as a result of shear force is called shear stress. Its formula is:
• Q7: Define Shear Stress.
  Ans:The stress produced as a result of shear force is called shear stress. Its formula is:
• Q8: Define tensile stress.
  Ans:The stress produced due to Tensile Force is Tensile Stress.
• Q9: Define compressive stress.
  Ans:The stress produced due to Compressive Force is Compressive Stress.
• Q10: Define Bending Stress.
  Ans:The stress produced by Bending Moment is Bending Stress.
• Q11: Enlist various modes through which forces affect structural members.
  Ans:Some of the modes are:

  1. ➔ Tension
  2. ➔ Compression
  3. ➔ Shearing
  4. ➔ Bending
  5. ➔ Torsion
• Q12: Differentiate between ordinary and pure bending.
  Ans:A bending moment produced by forces that do not form a couple is ordinary Bending.
  The bending moment produced by forces that form a couple is Pure Bending.
• Q13: Define Neutral surface.
  Ans:A neutral surface is the surface of a beam that does not undergo any tension or compression. At this surface, the force and its effects are zero.
• Q14: What do you know about section modulus?
  Ans:The ratio of Moment of Inertia and distance of extreme fibre from the centroidal axis is section modulus.
• Q15: State any two postulates of bending theory.
  Ans:Two points are:

  • ➔ Beam is straight
  • ➔ The material of beam is elastic
  • ➔ Hook’s Law is applicable to the material of beam
• Q16: State bending equation.
  Ans:where
  M = Bending Moment
  I = Moment of Inertia
  E = Young’s Modulus
  R = Radius of Curvature
• Q17: Define Direct Force.
  Ans:A direct force acts normal(perpendicular) to the object is called Direct Force.
• Q18: Define Shear Force.
  Ans:A shear force acts tangent(angle other than 900) to the object is called Shear Force.