# What are the Typical Derivatives in Mechanical and Electrical Components ?

Discussion in 'General Electronics Chat' started by darkmasta, Oct 25, 2009.

1. ### darkmasta Thread Starter New Member

Oct 25, 2009
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Hello,

Can someone PLEASE give me a site or a list of typical derivative components ?

These include di/dt ,dv/dt, dx/dt ...etc

For example :

For example :

dq/dt = i

dx/dt = v

di/dt = ?? (do you know what di/dt is ? Im not sure)

dv/dt = a

d^2x/dt^2 = a

and etc..

I really need it for my studies .. A test is coming soon and I need to study for it ..

Dm

Jul 7, 2009
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I think you're barking up the wrong tree -- you should learn the physical principles first and the basic math models will follow. Learning a bunch of formulas is meaningless and if that allows you to pass exams, then you're definitely in the wrong class -- your instructor should be teaching principles and using those principles to analyze and solve problems, not making you memorize dumb formulas -- that's what handbooks are for. Learn the principles and develop your intuition first.

3. ### darkmasta Thread Starter New Member

Oct 25, 2009
8
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Im sorry but I didnt say that I want to memorise them to pass exams ..

You are accusing me of that already ?

Sorry but I just wanted them to better understand the formulas ..

Inductance is v=L*di/dt ... I couldnt find what di/dt is, so I wanted to check online ..

Here is proof that im studying and not memorising ..

http://img39.imageshack.us/img39/6434/25102009093n.jpg

Do I really need to show all of this for what I asked for ? Im sorry to appear rude but I really hoped for a more helpful reply :S

Thank you,
Regards,
Dm

4. ### wr8y Active Member

Sep 16, 2008
232
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Well, the image you posted sure proved what you are doing!

Knowing this site, SOMEONE will come along with something that can help you. And I can't wait to see it.

5. ### Ratch New Member

Mar 20, 2007
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wr8y,

You are right about that, wr8y.

darkmasta,

I assume you know what defines a derivative. You can make a derivative out of any two quantities as long as they have a mathematical relationship to each other. Some common derivatives have names like current, which is dq/dt. Some don't have names, just descriptions; like dv/dt and di/dt are just voltage change per time and current change per time. So you just make up the derivatives as you need them, as long as you follow the mathematical rules and physical reality. Same goes for integrals, i.e. speed = ∫d(acceleration)*dt .

Ratch

6. ### darkmasta Thread Starter New Member

Oct 25, 2009
8
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Thanks for the replies

Ratch, so you're saying that di/dt does not really mean the derivative of another quantity ? such as how dq/dt = current ?

I didnt know that, thank you

A class with 150+ students makes it hard for me to ask such a simple question, so I had to revert to the net ..

I am going to ask him anyway if there is a list of the common derivatives as well, just to make sure I study them all for my course ... I will need to know them for the future as well..
Do you have any idea where can I find such site or any reference ?

Thank you

Mar 20, 2007
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darkmasta,