1. Define stress. When an external force acts on a body, it undergoes deformation. At the same ti... more 1. Define stress. When an external force acts on a body, it undergoes deformation. At the same time the body resists deformation. The magnitude of the resisting force is numerically equal to the applied force. This internal resisting force per unit area is called stress. Stress = Force/Area 2. Define strain When a body is subjected to an external force, there is some change of dimension in the body. Numerically the strain is equal to the ratio of change in length to the original length of the body.= P/A unit is N/mm^2 Strain = Change in length/Original length e = δL/L 3. State Hooke's law. It states that when a material is loaded, within its elastic limit, the stress is directly proportional to the strain. Stress α Strain σ α e σ = Ee E = σ/e unit is N/mm^2 Where, E-Young's modulus σ-Stress e-Strain 4. Define shear stress and shear strain. The two equal and opposite force act tangentially on any cross sectional plane of the body tending to slide one part of the body over the other part. The stress induced is called shear stress and the corresponding strain is known as shear strain. 5. Define Poisson's ration. When a body is stressed, within its elastic limit, the ratio of lateral strain to the longitudinal strain is constant for a given material. Poisson' ratio (µ or 1/m) = Lateral strain /Longitudinal strain 6. State the relationship between Young's Modulus and Modulus of Rigidity. E = 2G (1+1/m) Where, E-Young's Modulus K-Bulk Modulus 1/m-Poisson's ratio
1) What is the need to define ISA and give its values at standard sea level condition? Ans: Since... more 1) What is the need to define ISA and give its values at standard sea level condition? Ans: Since atmospheric conditions like pressure, temperature and density are constantly varying with altitude and location of the earth surface, there is a need for a normal atmosphere to use it as standard for the design and flight evaluation of aircraft all over the world. Its standard sea level values are, pressure = 1.013 x105 N/m2, temperature =288K, and density =1.225 kg/m3. 2) Define Geometric and Geopotential altitudes. Give the relation between 'g' at the Absolute altitude (ha) in terms of earth's surface gravity (go) and geometric altitude (hg) and radius of earth (r). Ans: Geometric altitude (hg) is the physical altitude above the sea level .Geopotential altitude (h) is the fictious altitude and differs from geometric altitude (hg) and is physically compatible with the assumption of constant acceleration due to gravity (go), ie; h = (g/go)0.5 hg. The ratio of acceleration due to gravity at an altitude ha, to that on the earth surface (go) is : g/go = (r/ha) 5) Define the terms (a) Pressure altitude (b) Temperature altitude (c) Density altitude. Ans: If an aircraft senses the actual outside air pressure which corresponds to some standard altitude ,then that altitude is called pressure altitude .Similarly if an aircraft senses the actual outside temperature and density which corresponds to some standard altitude , those are called temperature altitude and density altitude respectively. 6) What are the factors which decide the flying path of an airplane as a rigid body? Ans: Airplane as a rigid body its flying path is decided by , a) Its inertia characteristic. b) Earth's acceleration due to gravity c) Propulsive force generated by power plant d) Aerodynamic forces (L&D) and moments created on it due to the reaction between airplane and air.
1. Define stress. When an external force acts on a body, it undergoes deformation. At the same ti... more 1. Define stress. When an external force acts on a body, it undergoes deformation. At the same time the body resists deformation. The magnitude of the resisting force is numerically equal to the applied force. This internal resisting force per unit area is called stress. Stress = Force/Area 2. Define strain When a body is subjected to an external force, there is some change of dimension in the body. Numerically the strain is equal to the ratio of change in length to the original length of the body.= P/A unit is N/mm^2 Strain = Change in length/Original length e = δL/L 3. State Hooke's law. It states that when a material is loaded, within its elastic limit, the stress is directly proportional to the strain. Stress α Strain σ α e σ = Ee E = σ/e unit is N/mm^2 Where, E-Young's modulus σ-Stress e-Strain 4. Define shear stress and shear strain. The two equal and opposite force act tangentially on any cross sectional plane of the body tending to slide one part of the body over the other part. The stress induced is called shear stress and the corresponding strain is known as shear strain. 5. Define Poisson's ration. When a body is stressed, within its elastic limit, the ratio of lateral strain to the longitudinal strain is constant for a given material. Poisson' ratio (µ or 1/m) = Lateral strain /Longitudinal strain 6. State the relationship between Young's Modulus and Modulus of Rigidity. E = 2G (1+1/m) Where, E-Young's Modulus K-Bulk Modulus 1/m-Poisson's ratio
1) What is the need to define ISA and give its values at standard sea level condition? Ans: Since... more 1) What is the need to define ISA and give its values at standard sea level condition? Ans: Since atmospheric conditions like pressure, temperature and density are constantly varying with altitude and location of the earth surface, there is a need for a normal atmosphere to use it as standard for the design and flight evaluation of aircraft all over the world. Its standard sea level values are, pressure = 1.013 x105 N/m2, temperature =288K, and density =1.225 kg/m3. 2) Define Geometric and Geopotential altitudes. Give the relation between 'g' at the Absolute altitude (ha) in terms of earth's surface gravity (go) and geometric altitude (hg) and radius of earth (r). Ans: Geometric altitude (hg) is the physical altitude above the sea level .Geopotential altitude (h) is the fictious altitude and differs from geometric altitude (hg) and is physically compatible with the assumption of constant acceleration due to gravity (go), ie; h = (g/go)0.5 hg. The ratio of acceleration due to gravity at an altitude ha, to that on the earth surface (go) is : g/go = (r/ha) 5) Define the terms (a) Pressure altitude (b) Temperature altitude (c) Density altitude. Ans: If an aircraft senses the actual outside air pressure which corresponds to some standard altitude ,then that altitude is called pressure altitude .Similarly if an aircraft senses the actual outside temperature and density which corresponds to some standard altitude , those are called temperature altitude and density altitude respectively. 6) What are the factors which decide the flying path of an airplane as a rigid body? Ans: Airplane as a rigid body its flying path is decided by , a) Its inertia characteristic. b) Earth's acceleration due to gravity c) Propulsive force generated by power plant d) Aerodynamic forces (L&D) and moments created on it due to the reaction between airplane and air.
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