Help with understanding this momentum problem

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    Momentum Velocity
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Homework Help Overview

The discussion revolves around understanding a momentum problem, specifically focusing on the sign conventions used in physics regarding velocity directions during an impact scenario.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the implications of sign conventions for velocity, with one noting that the initial x velocity is positive and the post-impact x velocity is negative. Others elaborate on the typical conventions used in physics to define positive and negative directions.

Discussion Status

The discussion appears to be progressing with participants clarifying their understanding of the sign conventions. One participant expresses gratitude for the insights received, indicating a positive engagement with the topic.

Contextual Notes

There is mention of a link to a solution, but the focus remains on the conceptual understanding rather than specific problem-solving steps. One participant notes a delay in their responses due to internet issues, which may have affected the flow of discussion.

Kolika28
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Homework Statement
I understand the task and what I supposed to do. The only thing I don't understand is why I need a minus sign when calculating ##v_x##
Relevant Equations
##v_x=v*cos(\theta)##
1591012467673.png


Solution on the link: https://www.slader.com/textbook/9780321675460-university-physics-13th-edition/269/exercises/12/
 
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The initial x velocity of the ball is considered to be positive; therefore, the post impact x velocity is negative (opposite direction).
 
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Here we have the typical sign convention used in physics when we have movement along a line: we consider one direction (lets say to the right) positive while the opposite direction (to left) negative. So velocity is considered to be positive when it travels towards the right and becomes negative when it travels towards the left.
 
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Likes   Reactions: Kolika28 and Lnewqban
Sorry, for not answering before now. My internet has been down the last couple of days. I understand the minus sign now. Thank you so much for your answers, I really appreciate it!
 
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Likes   Reactions: Lnewqban and Delta2
You are welcome :smile:
 

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