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Depending on the source, I sometimes read $\frac{\delta q}{dt}$ , $\frac{dq}{dt}$ or even $\frac{\delta q}{\delta t}$ (rare)

Wich one is the correct notation ?

In theory we are to know if a differential form is exact before we can write $dq$ or $dt$, but how are we supposed to do that ?

Physics books usually choose a notation without giving much explanations... (actually I've only seen explanations about this in Thermodynamics, for $\delta Q$ and $\delta W$)

What tells me for sure that I can write $\vec{F} = \frac{d\vec{p}}{dt}$ ?

mwa1
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1 Answers1

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The notation whether it be d or delta doesn't matter as long as it describes an element (a minute amout) of the quantity.

Please keep in mind that this is NOT a ratio. So you can't write

dq = I. dt

This is mathematically wrong. As differentiation is an operation and not a mere ratio. It is like a machine and you can't separate it's parts or the machine won't work!

slhulk
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