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. ...
STRESS AND STRAIN - Stress- it is defined as the force acting per unit area of the cross- section of a body. it is denoted by f, P or σ ( Sigma ) . σ = P/A ( mathematically) Unit of stress :- N/m², N/ mm² = Pascal TYPES OF STRESS:- Mainly 2 types of stress 1.) Direct stress 2.) Shear stress 1.) Direct Stress - The force is applied perpendicular to the cross section of the body then the stress induce in body is known as direct stress. The direct stress either tensile or compressive. a.) Tensile Stress - when the axial pull is applied to the cross-section of a body then the stress induce is known as tensile stress. ( In a simple way tensile stress is the force whose effect tend to increase the length of the body) σ = P/A b.) Compressive Stress - when the axial push is a...