Is there an analytical solution to this equation?

In summary, the conversation discusses the rocket equation and the addition of air resistance. There are two models for air resistance and the speaker believes that the second model is more suitable for their purpose. They have derived a differential equation and are wondering if there is a solution. They also mention that there is no closed form solution for the equation unless certain parameters are set correctly. Finally, they suggest testing simplified equations on Wolfram Alpha to see if they have a solution.
  • #1
MigMRF
15
0
So I've derived the rocket equation in empty space and with constant gravity. Now I am interested in adding air resistance. I'm aware that there are 2 different models as if 0<Re<1 then F_drag=k*v and if 1000<Re<30000 then F_drag=1/2*A*rho*CD*v^2. And for my purpose the second model is most fitting (my Re is around 15000. So I've come up with a differentialequation and was wondering if there actually is a solution. Here is my equation:
1576411179923.png

So first of all, is the equation correct. I'm kind of new to differential equations.
And if it's correct then is there an analytical solution.

I'd like some help on this one :D
 
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  • #2
There's no closed form solution for that equation unless you find a way to set the mass loss rate, exhaust velocity and air resistance parameters just right to "accidentally" make this have a simple solution.

You can test this by putting some simplified equations of the same type, e.g.

##\displaystyle (1-at)\frac{d^2 x}{dt^2} =b-\left(\frac{dx}{dt}\right)^2##

to Wolfram Alpha for it to try to solve them.
 

1. What is an analytical solution?

An analytical solution is a solution to a mathematical problem that can be expressed using known mathematical operations, such as addition, subtraction, multiplication, division, and exponentiation. It is a closed-form solution that can be written in a finite number of steps.

2. How is an analytical solution different from a numerical solution?

An analytical solution provides an exact solution to a mathematical problem, while a numerical solution provides an approximate solution using numerical methods. Analytical solutions are often preferred because they are more accurate and provide a deeper understanding of the problem.

3. Can all equations have an analytical solution?

No, not all equations have an analytical solution. Some equations, such as transcendental equations, cannot be solved using known mathematical operations and require numerical methods to find a solution. However, many common equations, such as linear and quadratic equations, do have analytical solutions.

4. How do I know if an analytical solution exists for a specific equation?

There is no sure way to know if an analytical solution exists for a specific equation. However, if the equation is a commonly studied one and has a known analytical solution, it may be possible to find it through research or by consulting with other experts in the field.

5. What are the benefits of finding an analytical solution to an equation?

Finding an analytical solution can provide a deeper understanding of the problem and can be used to make predictions and solve related problems. It also allows for a more precise and accurate solution compared to numerical methods. Additionally, analytical solutions can often be expressed in a simpler and more elegant form, making them easier to work with and interpret.

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