Derivatives in Halliday's physics book?

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Discussion Overview

The discussion revolves around the differentiation of functions as presented in Halliday's physics book, specifically focusing on the derivative of the function 72t² and the confusion surrounding the results of basic differentiation and integration.

Discussion Character

  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant questions the result of the differentiation d(72t²)/dt = 144t, seeking clarification on the role of 'd' and 'dt' in the equation.
  • Another participant prompts for understanding of the definition of a derivative and asks about the derivative of f(x) = x².
  • A different participant mentions their understanding of integration and expresses confusion about arriving at the result of 144t from f(x) = x².
  • Several participants emphasize that the operation in question is differentiation, not integration, and suggest that a foundational understanding of calculus is necessary to grasp the concepts being discussed.
  • One participant notes that the thread's level was marked incorrectly for the type of questions being asked and adjusts it accordingly.

Areas of Agreement / Disagreement

Participants generally agree that the results discussed are basic derivatives and that a proper understanding of calculus is required. However, there is disagreement regarding the participant's understanding of the concepts, as some express confusion while others assert the need for foundational knowledge.

Contextual Notes

There is a lack of clarity regarding the participant's prior knowledge of calculus, which affects their understanding of differentiation versus integration. The discussion also highlights the importance of correctly identifying the level of questions being posed in relation to the expected responses.

Who May Find This Useful

This discussion may be useful for individuals seeking to understand the basics of differentiation and integration, particularly in the context of physics applications, as well as those looking to clarify their foundational knowledge in calculus.

kent davidge
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(sorry my bad english). I was reading a Halliday's book of phyisics awhat I found is below.

d(72t²)/dt = 144t

why did the result was 144? It has anything to do with the deltas in the equation (d and dt)?

and second I don't realize why the result of this another equation is this

4t²+2t+3 = 8t+2

5wgs5d.jpg
 
Last edited:
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These are very simple differentiations. What do you know of differentiating a function ? E.g. the definition of derivative?
The derivative of f(x) = x2 ?
 
well, I know a little bit how to solve an integral by summing all the terms but when I solve it for f(x) = x² I found 72t² and the result is 144t as you can see in the image above.
 
But this is not integration, it is differentiation !
 
This physics text is calculus based. You will need to learn calculus before attacking that text, I'm afraid.
 
I cannot do anything but agree with previous posters. These results are very basic derivatives and you will need to learn calculus properly before you can hope to understand what is going on.

Also, please note that the thread levels are intended for you to mark what level of answer you are comfortable with. The "A" you marked this thread with means that you expect an answer on graduate student level. This is clearly not the case and I have changed the level accordingly.
 
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kent davidge said:
d(72t²)/dt = 144t

why did the result was 144?

What did you think it should have been, and how did you arrive at that result?
 

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