Deriving Velocity and Acceleration from Position Vector r(t)

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Homework Help Overview

The discussion revolves around deriving velocity and acceleration from a given position vector of a particle moving along a space-curve, represented in vector form with Cartesian coordinates.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss differentiating the position vector to find velocity and acceleration. There is uncertainty about the correctness of the derivatives calculated by the original poster, with suggestions to double-check computations.

Discussion Status

Some participants have confirmed the general approach of differentiation, while others have pointed out potential errors in the derivatives. There is ongoing clarification regarding the correctness of the calculations, and participants are exploring the implications of these derivatives.

Contextual Notes

The original poster is navigating language barriers and is seeking confirmation on their mathematical approach. There is a mention of using LaTeX for mathematical notation, indicating a focus on proper representation in the forum.

GoodTimes
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Hello, I am new here, glad I found this Forum :0)
I am german and english is not my mother-tongue, so sorry in advance for any language-related mistakes

1. Homework Statement

i don't know how to make a vector arrow on a letter so I declare a v for vector as the following:
[PLAIN]http://upload.wikimedia.org/math/8/8/b/88b537be1c5870ce272a4dc9515bada9.png=vr(t) A particle moves on a space-curve, described by following position-vector:

[PLAIN]http://upload.wikimedia.org/math/8/8/b/88b537be1c5870ce272a4dc9515bada9.png= (t²+t)vex + (3t-2)vey + (2t³-4t²)vez

Homework Equations

The Attempt at a Solution



I think I might differentiate each part, but I am not sure,

I would do it like this

vr'(t)= (2t)vex + (3)vey + (6t² - 8t)vez
so this would be the velocityand vr''(t) = (2)vex + (0)vey + (12t - 8)vez
would be the acceleration
 
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Your problem statement does not include a question. Are you simply interested in finding the velocity and acceleration?

The basis vectors (in Cartesian coordinates) are constant so you can just differentiate the prefactors as you have done.

Edit: You can write mathematical notation on Physics Forums using LaTeX commands. Here is a very brief introduction. You can also press Reply on my post and you can see how I have done the following:
$$
\vec v(t) = \vec r'(t) = v_x \vec e_x + v_y \vec e_y + v_z \vec e_z
$$
 
Orodruin said:
Your problem statement does not include a question. Are you simply interested in finding the velocity and acceleration?

The basis vectors (in Cartesian coordinates) are constant so you can just differentiate the prefactors as you have done.

Edit: You can write mathematical notation on Physics Forums using LaTeX commands. Here is a very brief introduction. You can also press Reply on my post and you can see how I have done the following:
$$
\vec r(t)
$$

I am sorry, yes correct, my task is to find the velocity and the acceleration.
does your post mean that the two equations I've done are correct? so i could simply put in a t, for example t=2 and calculate it
 
The principle is correct, but one of your derivatives is not. I suggest you double check your computations (alternatively that you typed it in correctly, it may be a typo as well).
 
ahhh it is

$$
\vec r'(t) = (2t+1)\vec e_x + (3)\vec e_y + (6t²-8t)\vec e_z
$$
Orodruin said:
Your problem statement does not include a question. Are you simply interested in finding the velocity and acceleration?

The basis vectors (in Cartesian coordinates) are constant so you can just differentiate the prefactors as you have done.

Edit: You can write mathematical notation on Physics Forums using LaTeX commands. Here is a very brief introduction. You can also press Reply on my post and you can see how I have done the following:
$$
\vec v(t) = \vec r'(t) = v_x \vec e_x + v_y \vec e_y + v_z \vec e_z
$$
 
Correct.
 

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