inunits and dimensions why only meter length and time considered to be standards . why is every quatity expressed in these dimensions . what is the criteria

Dear garima,

We usually consider quantities like mass, length, time, and perhaps charge and temperature, as fundamental dimensions. We then express the dimensions of other quantitieslike speed, which is length/time, in terms of the basic set. The point is that every quantity which is not explicitly dimensionless, like a pure number, has characteristic dimensions which are not affected by the way we measure it. As we will see later, this provides a useful check on any calculations we do.

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Sagar Singh

B.Tech IIT Delhi