Need derivation of projectile motion

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Discussion Overview

The discussion revolves around the derivation of the equations of projectile motion, including aspects such as range, height, and distances along the X and Y axes. Participants seek to understand the mathematical formulation and underlying principles of projectile motion.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant requests the derivation of all four equations related to projectile motion, specifically mentioning range, height, and distances along the X and Y axes.
  • Another participant provides a link to an external resource for further information on projectile motion.
  • A third participant reiterates the same link and expresses gratitude for the assistance.
  • A detailed explanation is provided regarding the constant acceleration of a projectile, noting that it experiences downward acceleration due to gravity (g) and zero horizontal acceleration. The equations of motion are derived through integration, leading to expressions for vertical and horizontal displacement.
  • The explanation includes boundary conditions and discusses how initial angles affect the horizontal and vertical initial speeds, as well as how to determine landing positions using time derived from vertical motion.

Areas of Agreement / Disagreement

Participants do not appear to have reached a consensus on the derivation itself, as the initial request remains open and the responses include both external resources and a detailed mathematical approach without resolving the request for a complete derivation.

Contextual Notes

The discussion does not clarify specific assumptions regarding initial conditions or the context of the projectile's launch angle, which may affect the derivation of the equations.

piyush3dxyz
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Hey i need derivation of projectile motion..
All four equation..
including range,height,X-axis distance,y-axis distance..
 
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Try this: http://hyperphysics.phy-astr.gsu.edu/hbase/traj.html"
 
Last edited by a moderator:
Doc Al said:
Try this: http://hyperphysics.phy-astr.gsu.edu/hbase/traj.html"
thx a lot sir...
regards piyush...
 
Last edited by a moderator:
A projectile has constant acceleration downwards of g (roughly equal to 9.81m/s^2). And it has zero acceleration horizontally.

Since the acceleration is completely specified, we can use integration to find the laws of motion. Using z=upward and x being horizontal:

[itex]\ddot{z}=-g[/itex] and [itex]\ddot{x}=0[/itex]. Now using integration on both equations individually:
[itex]\dot{z} = \dot{z_0} -g(t - t_0)[/itex] and [itex]\dot{x} = \dot{x_0}[/itex] (where the subscript zero are constants - i.e. boundary conditions). So now we integrate the equations again to get:
[itex]z = z_0 + \dot{z_0}t -\frac{1}{2}g(t - t_0)^2[/itex] and [itex]x = x_0 +\dot{x_0}t[/itex]

These are all the laws of motion necessary. If you get a question that tells you the initial angle an object is fired at, then that gives you the ratio of the horizontal and vertical initial speeds. And if you get a question asking where an object ends up landing, then often you can solve for the vertical motion to get the time, and then use the time in the horizontal motion equation to get where it ends up landing.
 

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