Projectile Motion Equations with Non-Constant Acceleration

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Discussion Overview

The discussion revolves around the equations of projectile motion when acceleration is not constant. Participants explore the implications of variable acceleration on the standard kinematic equations and seek alternative formulations or approaches to address this scenario.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about equations for projectile motion under non-constant acceleration, suggesting a need for clarification on the topic.
  • One participant suggests that learning calculus is essential for understanding the underlying principles of variable acceleration.
  • Another participant proposes starting with Newton's second law (F=ma) and taking derivatives to analyze the time rate of change of acceleration.
  • A participant mentions that F=ma can be treated as a differential equation, indicating that integration can yield velocity or position as functions of time, contingent on knowing the force.
  • There is a question about whether the change in acceleration is constant, leading to a discussion on a series expansion for position based on initial conditions.
  • One participant references a standard kinematic equation and asks if there is a counterpart for cases where acceleration is not constant.
  • A later reply provides an integral formulation for position as a function of time when acceleration varies, which is acknowledged as helpful by another participant.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific equations or methods to apply for non-constant acceleration, and multiple viewpoints on how to approach the problem remain present throughout the discussion.

Contextual Notes

Participants express varying levels of familiarity with calculus, which may affect their ability to engage with the proposed methods. The discussion also highlights the complexity of applying Newton's laws under conditions of variable acceleration.

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Hi

Does anyone know the projectile motion equations in which the acceleration is NOT constant?
 
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Learn Calculus.

That's all you need.
 
ahh...

Isn't there an equation(s) derived from the kinematic ones i can just apply?
 
There is no way that anybody can guess what you are asking for. You will have to ask an understandable question.

As for variable accelerations, just apply Newtons 3rd:

F=ma
 
Nothing said:
Hi

Does anyone know the projectile motion equations in which the acceleration is NOT constant?
Isn't there an equation(s) derived from the kinematic ones i can just apply?

I believe you probably already know the standard proceedure here, Nothing.
Usually, beginning with F = ma,
just take the derivative of both sides of the equation since you are looking for the time rate of change of accel.

dF/dt = m(dA/dt)

However, the effectiveness of this equation goes beyond the original assumptions in Newton's law. In cases of rapid change of acceleration a modification of Newton's law is probable.

Is that what you are getting at?

Creator
 
F=ma is a differential equation since a =d^2 x /dt^2 with x, a and F vectors. Given a certain force you can find the velocity or position as a function of time by integrating the force respectively one or two times. But you indeed need to know some calculus for that...
 
Is the change in acceleration constant?

Doesnt:
Position = Sum(x(i)*t^i/i!)

where i goes from 0 to infinity, x(0) is initial position, x(1) is inital speed, x(2) is inital acceleration, etc...
 
ok u know that equation:

y = v0 sin (theta) - 0.5at^2 ?

where v0 sin (theta) is the vertical component the muzzle velocity

is there a counterpart where a is not constant?
 
Sure, you have:
y(t)=v_{0}t\sin\theta-\int_{0}^{t}(\int_{0}^{\tau}a(s)ds)d\tau
 
  • #10
thanks arildno, that really helped.
:smile:
 

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