Angle required to hit coordinates x, y, z with air ressitance

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Discussion Overview

The discussion revolves around calculating the angle required to launch a projectile to hit specific coordinates (x, y, z) while considering the effects of air resistance. It involves theoretical aspects of projectile motion, including the impact of gravity and resistive forces on the trajectory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a formula for calculating the launch angle, noting that it assumes only gravity acts as a resistive force and does not account for air resistance.
  • Another participant suggests that there is no analytic solution available and implies that numerical methods will be necessary to address the problem.
  • A question is raised about incorporating air resistance into the calculations, with a reference to external ballistics for further reading.
  • A later reply indicates that the drag model being used may be unconventional and suggests it might only be suitable for short flight times.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how to incorporate air resistance into the projectile motion calculations, and there are competing views regarding the appropriateness of the drag model being used.

Contextual Notes

The discussion highlights limitations in the current approach, particularly regarding the assumptions made about resistive forces and the need for numerical integration of motion equations.

TheShermanTanker
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The formula for the angle required for you to launch a projectile with a given velocity, gravity, distance and height difference is, taking g as gravity, v as total velocity, x as total distance on the horizontal plane and y as how high the target is above you (Negative value means the target is below you) is
tan-1((v^2 +/- square-root(v^4 - g(gx^2 + 2yv^2)))/gx). However, this assumes that the only resistive force is on the vertical plane (gravity) and that there is no horizontal resistance present (air resistance). However, the thing that I'm working on now has a hard-coded air resistance value of 1% of the object's current velocity that takes effect every 1/20 of a second (Basically imagine taking the object's velocity and multiplying it by 99% every twentieth of a second). Is there a way to factor air resistance in as well?
 
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Hello Tanker, ##\qquad## :welcome: ##\qquad## !

No analytic expression, I am afraid. So you have your numerical work (in the other thread) cut out for you :wink:

By the way, better not to call gravity force 'resisitive': it is a so-called conservative force: the work it does is converted into kinetic energy. For resisitive forces the work goes into heat and/or deformation.
 
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TheShermanTanker said:
Is there a way to factor air resistance in as well?
Have you been doing any reading about "External Ballistics"? https://en.wikipedia.org/wiki/External_ballistics

I'll also page @Dr. Courtney to see if he has better links or thoughts. :smile:

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No closed for solution. As mentioned above, the needed approach is to integrate the equations of motion.

But the drag model you are working with seems unusual and slightly contrived. It might work ok for relatively short flight times.
 
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