Could you help me solve first order diff eq?

In summary, the conversation discusses various techniques for solving the differential equation dv/dt=g-(k/m)*v^2. These include using standard integrals, separation of variables, and transforming the integral using partial fractions. However, there may be errors in the calculations and it is recommended to refer to a list of standard integrals for assistance.
  • #1
hangainlover
83
0
dv/dt=g-(k/m)*v^2
i thought about all sorts of diff eq solving techniques
but nothing comes up to my mind

dv/(g-(k/m)*v^2)=dt
but it doesn't really help ...
 
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  • #2
I think it's quite correct, but there could be some errors in calculation..anyway:

http://spiro.fisica.unipd.it/~mimo/altro/sol.JPG
 
Last edited by a moderator:
  • #3
hi hangainlover! :smile:

(try using the X2 tag just above the Reply box :wink:)

learn your list of standard integrals from the pf library :wink:
 
  • #4
Separation of variables seems to work. Just try to transform the integral [tex]\int \frac{1}{g-\frac{k}{m}v^2}dv[/tex] to the case xxvi of the standard integrals link provided by tiny-tim.
 
  • #5
Specifically,
[tex]g- \frac{k}{m}v^2[/tex]
, being a "difference of squares", factors as
[tex](\sqrt{g}- \sqrt{k/m}v)(\sqrt{g}+ \sqrt{k/m}v)[/tex]
and so that function can be integrated by "partial fractions".
 

1. What is a first order differential equation?

A first order differential equation is a mathematical equation that involves an unknown function and its derivative (or rate of change). It is called "first order" because it only involves the first derivative of the function.

2. How do I solve a first order differential equation?

To solve a first order differential equation, you need to find the function that satisfies the equation. This can be done using various techniques such as separation of variables, integrating factors, or using specific formulas for certain types of equations.

3. What is the difference between an ordinary and a partial differential equation?

An ordinary differential equation involves a single independent variable, while a partial differential equation involves multiple independent variables. This means that the solution to a partial differential equation is a function of more than one variable.

4. Can I solve a first order differential equation without knowing the initial conditions?

No, it is not possible to find a unique solution to a first order differential equation without knowing the initial conditions. These initial conditions provide the starting point for finding the solution, and without them, the solution would be a general solution rather than a specific one.

5. How are first order differential equations used in science?

First order differential equations are used in many fields of science, including physics, chemistry, biology, and engineering. They are used to model and describe various physical phenomena, such as the growth of populations, the decay of radioactive substances, and the motion of objects under the influence of forces.

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