A second order nonlinear ODE? Whoa

In summary, the conversation discusses solving the ODE \frac{d^{2}y}{dt^{2}} + t^{2} \frac{dy}{dt} + y^{2} = 0 with given initial conditions of y(0)=0 and y'(0)=0. The question is whether the equation is solvable or if there is a typo. The conversation concludes that the equation is actually quite simple and easily solved by inspection, and that the given initial conditions make it trivial to solve.
  • #1
sciboinkhobbes
22
0

Homework Statement


I'm not sure if this is actually solvable, or a typo on my homework... but here's the problem in question:

Solve the ODE:
[tex]\frac{d^{2}y}{dt^{2}} + t^{2} \frac{dy}{dt} + y^{2} = 0, y(0)=0, y'(0)=0[/tex]Attempt at solution
I've been stumped on where to even start with this one, but I attempted to substitute [tex]v=y'[/tex]. That didn't get me very far though, so any tips on where to start would be appreciated!

Typo-wise, I'm also wondering if perhaps the [tex]y^{2}[/tex] in the equation is actually just supposed to be a y... which would make it significantly easier.
 
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  • #2
This looks almost like a trick question...given your initial conditions, what will [itex]y''(0)[/itex] be? What then would you expect [itex]y'(0+dt)[/itex] and [itex]y(0+dt)[/itex] to be?...Do you see where this is going?
 
  • #3
sciboinkhobbes said:

Homework Statement


I'm not sure if this is actually solvable, or a typo on my homework... but here's the problem in question:

Solve the ODE:
[tex]\frac{d^{2}y}{dt^{2}} + t^{2} \frac{dy}{dt} + y^{2} = 0, y(0)=0, y'(0)=0[/tex]


Attempt at solution
I've been stumped on where to even start with this one, but I attempted to substitute [tex]v=y'[/tex]. That didn't get me very far though, so any tips on where to start would be appreciated!

Typo-wise, I'm also wondering if perhaps the [tex]y^{2}[/tex] in the equation is actually just supposed to be a y... which would make it significantly easier.
Actually, this whole problem is trivial! What is the easiest possible function that satisfies y(0)= 0, y'(0)= 0? Can you show that that is a solution to the differential equation? And, of course, by the "existence and uniqueness" theorem, it is the solution.
 
  • #4
Ooooooh...

Okay, that makes perfect sense! I was making it out to be a lot harder than it was, and wasn't trying to solve it by inspection, but after looking at it with your hints, it's very clear.

Thank you both!

Just out of curiosity, if the initial conditions weren't given, would it be solvable analytically?
 

FAQ: A second order nonlinear ODE? Whoa

What is a second order nonlinear ODE?

A second order nonlinear ODE (ordinary differential equation) is a mathematical equation that involves a function and its first and second derivatives, where the function is nonlinear (i.e. not a straight line) and the highest derivative is of second order.

How is a second order nonlinear ODE different from a first order nonlinear ODE?

A second order nonlinear ODE involves two derivatives of the function, while a first order nonlinear ODE involves only one derivative. This means that a second order nonlinear ODE is more complex and typically has a wider range of possible solutions.

Can a second order nonlinear ODE have multiple solutions?

Yes, a second order nonlinear ODE can have multiple solutions. This is due to the nonlinearity of the function, which can lead to different behaviors and solutions for different initial conditions.

How do you solve a second order nonlinear ODE?

The process of solving a second order nonlinear ODE varies depending on the specific equation. In some cases, an analytical solution can be found using mathematical techniques such as separation of variables or substitution. In other cases, numerical methods such as Euler's method or Runge-Kutta methods can be used to approximate a solution.

What are some real-world applications of second order nonlinear ODEs?

Second order nonlinear ODEs have many applications in physics, engineering, and other fields. Some examples include modeling the motion of a pendulum, describing the behavior of a damped harmonic oscillator, and analyzing the dynamics of chemical reactions.

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