Solving Questions with Variable Mass: Seeking Guidance

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Discussion Overview

The discussion centers around the challenges of solving problems involving variable mass in physics. Participants explore methods for approaching these types of questions, seeking guidance and examples to clarify the concepts involved.

Discussion Character

  • Homework-related
  • Exploratory

Main Points Raised

  • One participant expresses difficulty in solving questions with variable mass and requests guidance on the best approach.
  • Another participant suggests that providing a specific example of a problem would be beneficial for discussion.
  • A suggestion is made that the homework forums may be more suitable for this type of inquiry, as they are designed to assist with finding errors and misconceptions.
  • It is noted that when mass is variable, momentum must be considered, as some of it is carried away with the changing mass.
  • A mathematical formulation is presented, indicating that the relationship between force and variable mass can be expressed as "F= \frac{d(mv)}{dt}= ma+ v\frac{dm}{dt}".

Areas of Agreement / Disagreement

The discussion does not reach a consensus on a specific method for solving variable mass problems, and multiple perspectives on how to approach the topic are present.

Contextual Notes

Participants have not provided specific examples of problems, which may limit the depth of the discussion. The conversation remains exploratory without definitive solutions or methodologies being established.

MMS
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Hello everyone.

I've been struggling with how to deal or solve questions that include variable masses. Considering the method I usually try to solve with, it either gets me lost or just makes things complicated and doesn't work often to me. :P

I was wondering if you guys could help me out and tell me what is the best way to approach questions with variable mass and how to actually solve them. examples would also help a lot.


Thank you!
 
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Yes, "examples would help a lot". How about showing one? That is, show a specific problem you are having trouble with.
 
One of our homework forums would be the best place to do this, even if it's not an actual assignment for a class. The "homework helpers" are used to helping people find errors and misconceptions.
 
Usually, the mass has to go somewhere, so some of the momentum goes with it.
 
If m is variable then "F= ma" (force equals mass times acceleration) becomes "[itex]F= \frac{d(mv)}{dt}= ma+ v\frac{dm}{dt}[/itex]".
 
First of all thank you all for the replies. As soon as I get troubled again with a problem, I'll make sure to post it here before looking at its solution.
 
MMS said:
First of all thank you all for the replies. As soon as I get troubled again with a problem, I'll make sure to post it here before looking at its solution.

Not quite EXACTLY here in Classical Physics, I hope :smile:
Post it to one of our homework forums.
 

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