So, I drew a picture..

We have 3 masses in a triangle, obvious they are all attracted together, yet they ask for the Fnet on B. Overall I can do questions like these in linear, yet when it comes to this question is stumped me, would be have like a vector (direction) in the final answer? I honestly don't know were to start. Am I even doing this right? Could someone please explain to me were to continue or what I am doing wrong and guide me though it. Greatly appreciated, thanks! HelpPlease


closed as off-topic by Jerry Schirmer, Kyle Kanos, dmckee Jul 15 '15 at 2:03

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – Jerry Schirmer, Kyle Kanos, dmckee
If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Please note that Physics.StackExchange is not a homework help site. Please read this Meta post on asking homework-like questions and this Meta post for "check my work" problems. $\endgroup$ – Kyle Kanos Jul 15 '15 at 1:35
  • $\begingroup$ Fair enough, do you guys have an area to post them? I read though your article and it does not seem to have a solid awnser for its "up to debate". I understand its not a high level physics question but to me its still over my head at this level. I did use the homework and exercises tag, I also did describe were I couldnt continue and the general term of dynamics is over my head sometimes so I thought maybe others wouldnt mind :( Sorry.. $\endgroup$ – LostAtPhysics Jul 15 '15 at 1:53
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    $\begingroup$ There is not currently a homework help site associated with StackExchange for physics and every proposal on Area 51 ends up being closed due to lack of interest. And AFAICT, there is no debate on HW questions; asking "Am I doing this right?" isn't a concept. $\endgroup$ – Kyle Kanos Jul 15 '15 at 2:04
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    $\begingroup$ Just like in every other facet of life, there are those that ignore rules set up by others. Some do it because they don't care for rules, others do it because they're ignorant of the rules; either way, just because someone answered doesn't mean it's not against the rules. There have been posts on the Meta site about eliminating the homework tag, but so far they've not been accepted. $\endgroup$ – Kyle Kanos Jul 15 '15 at 2:12
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    $\begingroup$ The HW policy, as stated in the 1st link I gave, is that you ask about the concept that arose during your HW that is causing you to not complete the assignment and not "How do I do this?" or "Is this right?" $\endgroup$ – Kyle Kanos Jul 15 '15 at 2:19

It seems you pretty well understand how to find the pairwise forces and you are just having trouble adding them to get the net force. Since the forces are vectors, you need to add them like vectors. I assume this is difficult to imagine because you are just learning what a force is and you are just learning what vector addition is.

So think about something you are more comfortable with. Imagine that you have a vector displacement to the north and another displacement to the east. Now try to add them to get the net (that is, total) displacement. You should get something to the northeast. Now you just apply the same reasoning to the force vectors. The pull to the north adds with the pull to the east to give you a pull to the north east.

As you would find with the displacement, there are two ways of representing this resultant vector. You can give the components along the north and east directions (in which case the picture you gave is already a compelete solution), or you can give the magnitude and direction. I recommend you try to do it both ways.

Another relatively minor point is that you should be more careful about your units.


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