B How to describe complicated dimensions?

[NODARman]

TL;DR Summary

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Hi, just wondering if the dimension of velocity is m/s that can be described as what distance is passed in a specific time, then how can I describe volt which is kg•m²÷s³÷A? Mass in the area that moved...
I can't even imagine.

Thanks.

 

[DaveE]

It makes more intuitive sense to me if you substitute $A=\frac{C}{s}$, electric charge per second. Then you can have $V=\frac{[kg⋅(\frac{m}{sec^2})]⋅m}{C}$ which is like Work (=force⋅distance) per Coulomb.

 

[DaveE]

BTW, why did the SI gurus choose Amps instead of Coulombs as a basic unit? Charge seems to me to be as basic as it gets.

 

[Drakkith]

BTW, why did the SI gurus choose Amps instead of Coulombs as a basic unit? Charge seems to me to be as basic as it gets.

I think it was because when SI units were first introduced it was much, much easier to accurately measure current compared to measuring charge.

 

[DaveE]

Anyway, I think the more general answer is to try to regroup all of those dimensions into things that are more intuitive, like force, acceleration, charge, etc.

 

[Vanadium 50]

Why is there a kg?

What is the definition of an Ampere?
What is the definition of the Coulomb?
Whats' the definition of the Newton?

BTW, why did the SI gurus choose Amps instead of Coulombs

Easier to realize the standard. Measuring current is a lot easier than measuring charge.

 

[Baluncore]

... then how can I describe volt which is kg ·m² /s³ /A ?

There are many ways to factorise the dimensions of the volt.
Pick one that is simple and useful.
volt = joule / coulomb .

 

[Baluncore]

BTW, why did the SI gurus choose Amps instead of Coulombs as a basic unit?

The force between two wires, in a current balance, is proportional to the product of the currents.
amp = coulomb / second