By Jakob Kotas

Menlo College, Atherton CA USA

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Basic projectile motion without air resistance typically assumes gravity is constant. In reality, the acceleration due to gravity is proportional to the inverse-square of the distance between the centers of mass of the Earth and the projectile. When projectiles are near to Earth's surface, this deviation is negligible, but it becomes important when dealing with projectiles at high altitudes. We lay out a technique narrative for such a case which is a second-order, linear, constant-coefficient, and non-homogeneous ordinary differential equation (ODE). Through the course of the scenario, students will solve the ODE analytically and investigate its behavior numerically. They are also walked through the idea of linearizing a nonlinear ODE and discover the pitfalls in solving the approximate version. Along the way, they are introduced to the hyperbolic sine and cosine functions.

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Researchers should cite this work as follows:

  • Jakob Kotas (2022), "4-036-S-AltitudeDependentGravity," https://www.simiode.org/resources/9019.

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