# Cant grasp difference between infinitesimal change and macroscopic change

## Main Question or Discussion Point

What does infinitesimal change in V mean? Can someone please illustrate with simple example.

Lecture notes say infinitesimal change in V = dV
And large change in V is delta V.. I dont understand what it means though

chemisttree
Homework Helper
Gold Member
Infitesimal change is something like.... change in volume = 0.0000000001L

large change is something like... change in volume = .5L

http://en.wikipedia.org/wiki/Infinitesimal" [Broken]

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In the context of your textbook, was it just referring to magnitude or was it also using that as a way of saying, "change below the limit we need to be concerned with."?

I think this is more of a mathematical question, try and ask the question on the math board (calculus section).

It's like when you try and deduce the average speed of a car, when you know it travelled 10m in 2s, the average speed during those 2 seconds is 5m/s, and that's delta(x)/delta(t). If you want to know the exact speed at one particular moment in time, you need the function of x(t) and derive it, being dx/dt, so the infinitesimal change in position divided by the infinitesimal change in time.

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