Criteria S.I. Engine (Petrol or Spark Ignition Engine) C.I. Engine (Diesel or Compression Ignition Engine) Working Cycle Works on Otto Cycle or Constant Volume Cycle. Works on Diesel Cycle. Mixture During Suction Stroke Takes a mixture of air and petrol during the suction stroke. Takes only air during the suction stroke. Fuel Used Uses petrol as fuel. Uses diesel as fuel. Compression Ratio Has a compression ratio that varies from 6 to 10. Has a compression ratio that varies from 16 to 20. Engine Weight and Cost S.I. engines are lighter and cheaper. C.I. engines are heavier and costlier. Initial Cost Initial cost is lower compared to C.I. engines. Initial cost is high due to high compression ratio. Starting Starting is easy. Starting is difficult, especially in cold conditions. ...
• ELASTICITY:- It is the property by virtue of which the body regaina it's original shape and size after when load is removed.
This law states that when a material is loaded within limit of proportionality, the strain is directly proportional to stress.
Thus Strain, E Stress, o (within limit of proportionality)
ELASTIC CONSTANTS:- there 3 Elastic constants
1.)Modulus of Elasticity or Young's Modulus: It may defined as the ratio of tensile stress and tensile strain or ratio of compressive stress and compressive strain.
It is denoted by E
It has has the same units as that of stress, i.e. N/m², N/mm² or Pa
2.) Modulus of Rigidity or Shear Modulus: The ratio of shear stress and shear strain is known as modulus of rigidity or shear modulus.
This is denoted by G. C or N
G = shear stress (τ)/ shear strain (ϕ.)
3.) BULK MODULUS:- it is the ratio of Normal stress to the Volumetric strain.
It is denoted by K
Unit of bulk modulus is N/m², N/mm² or Pa
RELATION BETWEEN ELASTIC CONSTANTS
