Adding Velocity and Acceleration

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Discussion Overview

The discussion revolves around the concepts of velocity and acceleration in the context of particle motion, specifically how to calculate new positions and velocities under constant and changing acceleration. It includes theoretical considerations and practical applications related to kinematics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant describes a scenario where a particle's initial position, velocity, and acceleration are given, and calculates the new position after one second using both velocity and acceleration.
  • Another participant suggests using the formula $$v = v_0 + at$$ to calculate the new velocity after a time interval under constant acceleration.
  • A participant raises a question about calculating velocity when acceleration is changing, specifically referencing gravitational acceleration with the formula $$a = \frac{GM}{r^2}$$.
  • Another participant reiterates the question about calculating velocity for a falling body under varying gravitational acceleration and provides a link to external resources for further information.

Areas of Agreement / Disagreement

Participants express different approaches to calculating velocity and acceleration, with some focusing on constant acceleration and others on changing acceleration. The discussion does not reach a consensus on the best method for varying acceleration.

Contextual Notes

There are limitations regarding the assumptions made about constant versus changing acceleration, and the impact of external factors such as air resistance is noted but not resolved.

Who May Find This Useful

This discussion may be useful for students and enthusiasts of physics, particularly those interested in kinematics and the effects of acceleration on motion.

Phys_Boi
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So if a particle is at (0,0) and has a velocity of <-3,0> and an acceleration of <-2,-4> then we would add them to get the new position...

With a time interval of one second (t=1) then due to velocity:
Δx = -3(1) = -3
Δy = 0(1) = 0

then due to acceleration:
Δx = ½ (-2) (1)^2 = ½ (-2) = -1
Δy = ½ (-4) (1)^2 = ½ (-4) = -2

so we can add these displacements to get a new position of (-4, -2)

So my question is: after we arrive at this point and the acceleration has affected the velocity (and assuming the acceleration continues) is there another velocity vector? Or is there just the acceleration? Basically, do you only use the velocity once and forget it? Or does it still exist, and if so, how do you calculate it?

Thank you for any help!
 
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For a constant acceleration, you can calculate the velocity of an object with the formula $$v = v_0 + at$$ where ##v_0## is the initial velocity before you start timing, and ##v## is the new velocity after a time ##t##, if the object experiences a constant acceleration ##a##. Using this formula you should be able to calculate the new velocity of the particle after one second
 
So I'm using gravitational acceleration..
a = GM/r2

how would I calculate the velocity for this changing acceleration?
 
Phys_Boi said:
So I'm using gravitational acceleration..
a = GM/r2

how would I calculate the velocity for this changing acceleration?

If you need to calculate the velocity of a falling body, where the acceleration due to gravity varies, have a look at this link

https://en.wikipedia.org/wiki/Equations_for_a_falling_body

Note that these formulae don't take into account factors like air resistance, etc.
 
Thank you sir
 

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