Solve second order nonlinear differential equation

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SUMMARY

The discussion focuses on solving the second-order nonlinear differential equation y'' + k/(y^2) = 0, derived from Newton's second law of motion for an object falling under gravitational force. A key insight provided is the method of finding a first integral through energy conservation by multiplying the equation by the time derivative, denoted as ˙y. This transforms the equation into a first-order equation suitable for separation of variables, leading to a solution.

PREREQUISITES
  • Understanding of differential equations, specifically second-order nonlinear types.
  • Familiarity with Newton's laws of motion and their applications.
  • Knowledge of energy conservation principles in physics.
  • Proficiency in solving first-order differential equations using separation of variables.
NEXT STEPS
  • Study the method of finding first integrals in differential equations.
  • Learn about energy conservation in the context of mechanical systems.
  • Explore techniques for solving first-order differential equations, particularly separation of variables.
  • Investigate applications of nonlinear differential equations in physics and engineering.
USEFUL FOR

Students and professionals in physics and engineering, particularly those dealing with mechanics and differential equations, will benefit from this discussion.

Alfredo1511
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how do you solve this equation?

y´´ + k/(y^2) = 0 ? I got it from applying Newton's 2nd law of motion to an object falling from space to Earth only affected by gravitational force. Thank you!
 
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Is this a homework problem? If so, you should post it in the homework section. So I'll give only a hint to the solution:

You can find a first integral of the equation of motion, which is nothing than energy conservation, by multiplying with ##\dot{y}## (assuming that your prime means in fact a time derivative). Then you get a first-order equation, which can be solved by separation of variables.
 

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