How do I calculate physics formulas containing derivatives and real numbers?

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Homework Help Overview

The discussion revolves around calculating physics problems involving derivatives, specifically in the context of impulse and force. The original poster expresses confusion about the application of derivatives in physics formulas and the implications of instantaneous changes in force.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to relate impulse to force using derivatives and questions the meaning of calculating force as time approaches zero. Other participants raise points about the physical implications of instantaneous collisions and the units involved in the calculations.

Discussion Status

Participants are exploring various interpretations of the original poster's questions. Some have offered insights into the nature of collisions and the mathematical representation of impulse, while others suggest that a deeper understanding of calculus may be beneficial. There is no explicit consensus, but the discussion is progressing with multiple perspectives being shared.

Contextual Notes

There are mentions of assumptions regarding the duration of collisions and the nature of forces being constant over time intervals. The original poster's repeated confusion indicates a need for clarification on fundamental concepts in calculus as they apply to physics.

NODARman
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Homework Statement
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Relevant Equations
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Hi, I'm trying to calculate my own physics problem but didn't get it something.
When I'm trying to calculate the impulse of the object when it's hit by F=10N force in the smallest possible time, then should I write:
dP/dt = Fnet => dP = Fnet*dt ?

Another question: In general, if I calculate just a net force, we know that the derivative of the constant is zero. Then if dP is 10 N/s and t->0 therefore Fnet = 10/0 ?
What I don't get is how to calculate any physics formula which contains derivatives and real numbers.
 
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I don’t think any collision actually lasts 0 seconds. A collision that lasts 0 seconds is a collision that doesn’t actually happen.

Also ##dP## would have units of ##N \cdot s## not ##\frac{N}{s}##.
 
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These might help

and if ##\dfrac{\mathrm{d}p}{\mathrm{d}t} = F(t)## then ## \displaystyle \Delta p = \int_{t_1}^{t_2}F(t) \mathrm{d}t##
Now one can define the average constant force of impulse as ##<F> = \Delta p / \Delta t = \Delta p / (t_2 - t_1) ##
i.e. ## \displaystyle <F> = \dfrac{1}{t_2 - t_1} \int_{t_1}^{t_2}F(t) \mathrm{d}t## which you might remember from calculus class.
 
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NODARman said:
What I don't get is how to calculate any physics formula which contains derivatives and real numbers.
You could take a calculus course?
 
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NODARman said:
When I'm trying to calculate the impulse of the object when it's hit by F=10N force in the smallest possible time
There's no such thing as the smallest amount of time. Unless you mean zero, in which case no collision occurs. The collision must last for some nonzero amount of time, however small.
 
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NODARman said:
Homework Statement:: .
Relevant Equations:: .

What I don't get is how to calculate any physics formula which contains derivatives and real numbers.
You should not feel bad, it took a fellow named Newton to figure out how to deal with instantaneous change.
To any degree of approximation for a well behaved force, slicing time into finite intervals Δt, assuming the force is constant over that interval and summing will get you a numerical result to nearly any level of accuracy required.
But doing the clever stuff like calculating exact orbits for all time requires a leap of intuition. What happens to this rate of change as I slice time into infinitesimal pieces (dt) ?? The answer is called The Calculus and it is a touchstone for human ingenuity. It is not easy.
 
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