Solving a hard DE: R'(t)=k*4*pi*R(t)^2

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In summary, the conversation involves solving a first-order differential equation and checking if the solution is correct. The conversation also touches on the difficulty of solving the equation and the use of technology to solve it.
  • #1
Mathman2013
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1
Homework Statement
solving the following ODE (Hard)
Relevant Equations
R'(t)=k*4*pi*R(t)^2
I have the following DE, R'(t) = k*4*pi*R(t)^2, where R(0) = 5, and R'(0) =-0.001. I have attempted to solve it Maple, and would like to know if I have done it correctly?
maple_file.png
 
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  • #2
Mathman2013 said:
would like to know if I have done it correctly
The way to check that you (Maple?) have done it correctly is to differentiate twice and see if it matches !
You don't need PF to do that for you, do you :wink: ?

[edit] and what about entry 1 ?
[edit2] Strike the 'twice' o:) :wink: .

##\ ##
 
Last edited:
  • #3
BvU said:
The way to check that you (Maple?) have done it correctly is to differentiate twice and see if it matches !
You don't need PF to do that for you, do you :wink: ?

[edit] and what about entry 1 ?

##\ ##

I can't find k if I select entry 1.
 
  • #4
How wold you go about if you had to solve this DE yourself ?

You mention 'hard' but it really isn't difficult ...

##\ ##
 
  • #5
BvU said:
The way to check that you (Maple?) have done it correctly is to differentiate twice and see if it matches !
The DE is first order, so the OP needs only to differentiate the solution function once.
 
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  • #6
This DE is solvable by hand. Notice that the original equation can be written as
dR/R^2 = Constant*dt
 
  • #7
  • #8
BvU said:
What are you asking?
 
  • #9
BvU said:
How wold you go about if you had to solve this DE yourself ?
 
  • #10
Wrong mathman. You want the 2013 edition.
 
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  • #11
Oops ! o:) sorry.
 
  • #12
If this DE is hard, I wonder what this topic looks like when the variables are not separable :P
 
  • #13

Related to Solving a hard DE: R'(t)=k*4*pi*R(t)^2

1. What is a hard DE?

A hard DE, or hard differential equation, is a type of mathematical equation that involves one or more derivatives of an unknown function. These equations are often difficult to solve analytically and require advanced mathematical techniques.

2. What does R'(t) mean in this equation?

R'(t) represents the derivative of the function R(t) with respect to time. In other words, it is the rate of change of the function at a specific time t.

3. How do you solve a hard DE?

Solving a hard DE typically involves using a combination of mathematical techniques, such as separation of variables, substitution, and integration. It may also require knowledge of specific solution methods for different types of DEs.

4. What is the significance of k in this equation?

In this equation, k represents a constant that affects the rate of change of the function R(t). It could represent a physical constant or a parameter in the equation that affects the behavior of the function.

5. How does this equation relate to real-world problems?

This type of DE, known as a population growth equation, can be used to model the growth of a population over time. The function R(t) represents the population size at a given time t, and the constant k represents the growth rate of the population. This equation can also be applied to other areas, such as physics and chemistry, to model the behavior of various systems.

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