ANSWERS: 2

The metric system provides many units for length, weight and time, related by powers of ten, and units derived from these. The two most popular systems were CGS, where all the units were based on centimetre, gram and second; and MKS where the units are based on the metre, kilogram and second. As an example, in the CGS system, the unit of force is the dyne, which is roughly the weight of the smallest insect, the parasitic wasp, or the weight a 2mm by 2mm square of thin paper. In the MKS system the units tend to come out at a more everyday scale: the unit of force is the Newton, which is the weight of 100grams. The SI system standardized on the MKS system and added Kelvin, ampere, mole and candela to the three basic units. All countries use the SI system to some extent. For instance, a lb (international avoirdupois pound, as used in the US and the UK) is now *defined* as exactly 0.45359237 kg. So even when you think you aren't using the metric system, you probably are!

In MKS system we use kg for mass ,m for length and sec for time .These three only are taken as fundamental one. But in the case of SI system we have four more fundamental ones kelvin ,ampere ,mole and candela . In case of SI system we use only one unit for energy i,e joule for any form of energy .Bcoz we can use calorie , watthour and joule for the energy in Mks . to avoid this confusion we can make use of it
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