For example, when we want to represent speed, measured in meters per second, we are taught to write it as m/s , but why exactly do we divide meters (m) by seconds (s)?
Or, as for another example, in calculus, to represent a change of one quantity (call it "y") with respect to (or "per") another quantity (call it "x"), we write: dy/dx , or dy "divided by" dx. But, again, why division? What exactly is being "divided" here? How can I visualize this?
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$\begingroup$"Per" may be short for a "part of", "fraction of" , " pertaining to" or " pertaining to units of" &c.
Sixty percent is 60 in fraction of 100, implying division as the needed operation here.
It may also be short for " for each" ; 60 kmph is 60 km for each hour, and since the total km distance is a multiple of 60, "per" denotes the opposite, in sense of division.
It may have originated from the Sankrit word "prathi," meaning each, every..
$\endgroup$ 2 $\begingroup$The term "per" in this context means "for each".
EG "10 m/s" means 10 m for each second
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