Can someone clarify some things for me?

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Homework Help Overview

The discussion revolves around understanding the variables and concepts related to 2D motion equations, specifically focusing on the definitions and roles of terms such as V, Vnaught, x, and y in the context of physics problems.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the definitions of variables related to motion, questioning the meanings of V, Vnaught, x, and y. There is an attempt to clarify the distinction between initial and current values of velocity, as well as the interpretation of position along coordinate axes.

Discussion Status

The discussion is active, with participants providing insights into the meanings of various terms and their applications in 2D motion problems. Some guidance has been offered regarding the use of subscripts to denote initial and final values, but there is still uncertainty regarding the application of these concepts in specific scenarios.

Contextual Notes

Participants express a lack of confidence in identifying and applying the correct variables in their problems, indicating potential confusion or misunderstanding of the foundational concepts of motion in two dimensions.

matt@USA
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I don't know if I am just looking too much into the problems or what, but I am having a very hard time determining what is what in the problems. I am not confident on what I pick as Vnaught, V, x, y, etc ... Will someone please help?
I will tell you how I determine it, and you can correct me.

x=where it lies on the x axis?
y=where it lies on the y axis? ... Both of these are determined by me? Correct?

So is V the velocity of the object? And what is Vnaught?

These are all pertaining to 2D equations.
 
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Naught is usually the initial value of something. If you have a position graph then you could say that x naught is the starting position of the object. You see subscripts used a great deal. i usually denotes an initial value as well, f usually means the final value. Aside from that everything else is pretty descriptive. When you are dealing with 2+d problems, you might see subscripts of x and y to let you know which component it is. Say you have a vector r, they might say that [itex]a_{rx}[/itex] is the acceleration of the x component of the r vector and so on.
 
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Yes, x and y are positions, measured along their respective coordinate axes.

v is velocity. In general it varies with time (i.e., pick a time t, and you'll get a specific value for v).

v0 is initial velocity (i.e. velocity at t = 0).
 
So what is V?
 
matt@USA said:
So what is V?

In the context you have provided, V would be the velocity at the time to are dealing with.

Vo is the initial velocity. V is the velocity later.

eg: you might want to know "if a stone is thrown vertically down from the top of a 30m tower with a velocity of 2 ms-1, how fast will it be traveling just before it hits the ground -[take g=10].

everything is happening downwards, so let down be positive.

Vo = 2.0
a = 10
x = 30
V = ??

Best formula to use would be

V2 = Vo2 + 2as

V2 = 4 + 2x10x30 = 604

so V = 24.6
 

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