Finding Instantaneous Acceleration in a Velocity-Time Graph

AI Thread Summary
To find instantaneous velocity at points A and B on a velocity-time graph, you can read the values directly from the graph since it plots velocity against time. However, if you're looking for instantaneous acceleration, it becomes more complex as the acceleration changes instantaneously between constant values at those points. There is no well-defined instantaneous acceleration at A and B due to this abrupt change. Creating a scatter plot of velocity points and fitting a line for average velocity may help in analyzing the data, but it won't resolve the issue of instantaneous acceleration directly at those points. Understanding the distinction between velocity and acceleration is crucial for accurate interpretation.
welai
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http://i52.tinypic.com/95zrsw.png

^ okay, if my velocity-time graph looks like that (it was a quick sketch), and I need to find the INSTANTANEOUS velocity at point A and point B, how do I do it?

I mean, I understand the slope of the tangent = instantaneous acceleration, but this is not a curve. Thus, I also understand to use the normal straight slope. But I don't understand, WHICH slope is the INSTANTANEOUS acceleration for those points?
 
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welai said:
http://i52.tinypic.com/95zrsw.png

^ okay, if my velocity-time graph looks like that (it was a quick sketch), and I need to find the INSTANTANEOUS velocity at point A and point B, how do I do it?

I mean, I understand the slope of the tangent = instantaneous acceleration, but this is not a curve. Thus, I also understand to use the normal straight slope. But I don't understand, WHICH slope is the INSTANTANEOUS acceleration for those points?

You read the instantaneous velocities at A and B directly from the graph (because your plot is v vs. t). On the other hand, if you meant to say instantaneous "acceleration" (not velocity), then at A and B there is *no well-defined value*: the acceleration changes instantly from one constant value to another, so the acceleration at one 100 billionth of a second before A is different than the acceleration at one 100 billionth of a second after A.

RGV
 


Ray Vickson said:
You read the instantaneous velocities at A and B directly from the graph (because your plot is v vs. t). On the other hand, if you meant to say instantaneous "acceleration" (not velocity), then at A and B there is *no well-defined value*: the acceleration changes instantly from one constant value to another, so the acceleration at one 100 billionth of a second before A is different than the acceleration at one 100 billionth of a second after A.

RGV

Thank you! Just another simple question, then would it be easier if I make a scatter-plot of my velocity points on my vt graph, then I'll find the line of best fit for average velocity, then find the instantaneous acceleration at the time interval of A and B?
 
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