A question from Resnik about g-force

In summary: So in −Fg=−mg, −Fg is 1D vector, m is scalar mass and −g is again a vector. And according to second law this is how we write the relation between force of gravity and downward acceleration. Force vector is equal to −mg vector.It does not mean we can cancel the -signs. We can omit it so that we can say F=ma(magnitude form). This is just stating the relation between gravitational force and it's acceleration g via second law.Yes, that is correct. The negative signs in the equation are just there to indicate the direction of the vectors. They do not affect the magnitudes of the quantities involved. So in the end, we can omit the
  • #36
hutchphd said:
An adjunct to this process for, shall we say, the less precise thinker (moi) is to cultivate that little inner voice that continuously asks "does that make sense?" in as many ways as is possible. This includes reflexively looking at units (dimension) and thinking about simplified limiting cases with every major calculational step. It is a very useful skill and has managed to keep me from becoming a complete lunatic worrying about signs. Purely defensive on my part but very useful for everyone.
Well I do that to a extent I get off topic. I hope you are not trying to say me a lunatic. It takes time to process all that and I am processing information. No way I am going blindly in one direction. But we make mistakes and I believe in one time or the other you are told of your mistake and it’s this one. I realized now I was thinking I know it but I don’t. It happens and it’s completely normal. You should understand this instead of just saying I am done with this. Maybe what is easy and completely irrelevant to you is not actually it.
 
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  • #37
rudransh verma said:
Exactly. I am one of those.
My hope is that you not only understand the difference between ##F## and ##\vec F## now but that you take away the more general lesson that the notation matters. Whereas before this thread, you may have thought ##p=mv## and ##\vec p = m\vec v## were the same equation, you'll now know they mean different things.
 
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  • #38
rudransh verma said:
Its the mistakes we do makes us learn anything. Spending time working out all the things which are wrong or not possible helps very much. Removing the wrong fog in the brain helps us to clearly see the truth. Solving problems is a great way to do it not just merely reading the texts.
Some expressed frustration earlier in the thread, but I wanted to say I think it's good that you even thought to ask your questions. You can't learn from your mistakes if you don't even realize you're making them.
 
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  • #39
vela said:
Some expressed frustration earlier in the thread, but I wanted to say I think it's good that you even thought to ask your questions. You can't learn from your mistakes if you don't even realize you're making them.
Ya! I come here with high hopes because I feel I can get my answers here from you guys.
 
  • #40
I certainly intended no offense to you. I was pointing out that the best answer to your question may not be the one you seem to be demanding. For me, such attention to detail would often preclude getting to a useful result. And it would indeed drive me crazy.
It was a suggestion learned from a lifetime. Sometimes the forest cannot be seen because of the trees, and you just keep going without really undrstanding. Eventually, if you take care, it works out.
 
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