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. ...
-Science is the knowledge about nature and the quantitative studies about nature,it's phenomenon and laws is called Physics.
*Dimensional Formula's of some common physical parameters
*PHYSICAL QUANTITIES- Any quantity that can be measured is called physical quantity.
Example- 1.you can measure length of a bed.
2. Height of tower
There are 2 types of quantity-
( 1.)Fundamental Quantity ( Mass, Length,Time)
( 2.)Derived Quantity ( Velocity, Force)
*UNIT- The Unit is a standard quantity which is used for measurement.
A Unit should have following properties
1. it should be well defined.
2. It should have proper size.
3. It not change with time ,place or physical condition.
Unit are classified as( Fundamental Unit,Derived Unit)
SYSTEM OF UNIT- 4 types of system
(1.) C.G.S system- which means Centimetre, Gram, Second.
( 2.) M.K.S system- Which means Metre,kilogram, Second.
( 3.) F.P.S system- Which means Foot, Pound, Second.
( 4.) International System of UNIT- This system is basically a modification over m.k.s system. It is based on seven base unit and two supplementary unit.
*SCIENTIFIC NOTATION AND PREFIX
*Dimensional Formula's of some common physical parameters