Force and Energy

*Popper*

Quote by g.lemaitre

Energy causes objects to move. Force causes object to change direction, accelerate or decelerate, correct?

This is an incorrect way of thinking about motion. A body in motion has energy. It is not the cause of the motion. A particle can be moving at constant body with nothing causing it to move.

To refer to force as causing acceleration used to be the way physicists looked at force. However in modern times we no longer think that way. Instead we define force a the time rate of change of momentum. When we look at particular sitations such as an electron in an electric field we can say that the electric field causes the electrons momentum to change. The rate of change is then quantified as F = dp/dt.

g.lemaitre

Quote by sophiecentaur

So, in the past, no one could have understood anything as a result of personal effort and reading? PF just wasn't around in the formative years of the really bright Scientists around today. The instant gratification in the form of answers from someone who has identified your personal mis-conceptions and then answering in just the right way would be an immense luxury, I think.

If you were prepared to PAY a personal tutor to be taught by the one-to-one question and answer method then you might find someone to indulge you. But it would cost you. If you lived locally, I would even offer, myself but I doubt whether you live in the South of England (statistically). Have you thought of reading all the faqs and searching the threads on this topic before leaping in half way through, trying to make spurious connections between random ideas?

If you are interested in making connections between Energy and Motion of particles, look up kinetic theory in any good text book or on the hyperphysics site (very well put together). There is a lot of info available for those who are prepared to read it.

It is easier to rid yourself of false beliefs by posing questions to experts than it is to read books written by experts. Let me prove this logically.

1. Expert says A and B are true, therefore I believe A and B mean that C is true.
2. If C is false and an expert is present, the expert will tell me
3. If C is false and an expert is not present, then the expert will not tell me.
4. Therefore, uttering beliefs in the presence of experts is the more likely to remove falsity of belief than uttering beliefs in the absence of experts.

Vanadium 50

Easier for you. Not easier for the experts whose patience you are testing. This is why we discourage this mode of behavior.

And just out of curiosity, exactly how much more valuable do you think your time is than ours?

g.lemaitre

Quote by Vanadium 50

Easier for you. Not easier for the experts whose patience you are testing. This is why we discourage this mode of behavior.

And just out of curiosity, exactly how much more valuable do you think your time is than ours?

If you feel like helping others is a waste of time, then why are you here?

Vanadium 50

Don't put words in my mouth.

You didn't answer my question. Exactly how much more valuable do you think your time is than ours?

sophiecentaur

Quote by g.lemaitre

It is easier to rid yourself of false beliefs by posing questions to experts than it is to read books written by experts. Let me prove this logically.

1. Expert says A and B are true, therefore I believe A and B mean that C is true.
2. If C is false and an expert is present, the expert will tell me
3. If C is false and an expert is not present, then the expert will not tell me.
4. Therefore, uttering beliefs in the presence of experts is the more likely to remove falsity of belief than uttering beliefs in the absence of experts.

This assumes that the 'experts' are actually disagreeing. In a matter as basic as this and at the level of your questions, can you say that the experts do actually disagree?
It seems to me that the main problem here is not bothering to read the small print in the definitions of the equantities involved. Only at a quasi philosophical level is there any possible discussion here.
It seems to have been a matter of asking rather than reading and thinking first.

g.lemaitre

Quote by sophiecentaur

This assumes that the 'experts' are actually disagreeing. In a matter as basic as this and at the level of your questions, can you say that the experts do actually disagree?
It seems to me that the main problem here is not bothering to read the small print in the definitions of the equantities involved. Only at a quasi philosophical level is there any possible discussion here.
It seems to have been a matter of asking rather than reading and thinking first.

Ultimately however a student can read A and B and falsely conclude C. Of course under rare occasions the student can read D and find out that C is false, but those occasions take time and are rare. And of course it is also the case that a student will believe C and one expert will say that C is true and another will say C is false but fortunately those situations are in the minority. Nevertheless, it is also true that the best way to liberate yourself from false belief is to utter your belief and see what people think of them. That's why I'm here trying to get my beliefs on energy straight.

I have decided however that my real area of misunderstanding is a false interpretation of HUP and the Law of Conservation of Momentum, which is why I have a thread open at the QM forum. I more or less consider this thread resolved.

sophiecentaur

Quote by g.lemaitre

Ultimately however a student can read A and B and falsely conclude C. Of course under rare occasions the student can read D and find out that C is false, but those occasions take time and are rare. And of course it is also the case that a student will believe C and one expert will say that C is true and another will say C is false but fortunately those situations are in the minority. Nevertheless, it is also true that the best way to liberate yourself from false belief is to utter your belief and see what people think of them. That's why I'm here trying to get my beliefs on energy straight.

I have decided however that my real area of misunderstanding is a false interpretation of HUP and the Law of Conservation of Momentum, which is why I have a thread open at the QM forum. I more or less consider this thread resolved.

"Best"? It may the the most convenient way to get 'an' answer but if the approach is just to ask random questions to random people, will the responses be reliable? Look at some of the threads on PF, the questions are often so vague that it takes a page of posts before the actual question reveals itself. This is often because the question is little more than a phishing exercise and was put together with little effort. Imo, an OP should be written with care so that people can start to answer it in a useful way. What did this OP mean? Where was the source 'expert' opinion that "Energy causes objects to move"?

DaleSpam

Quote by g.lemaitre

Nevertheless, it is also true that the best way to liberate yourself from false belief is to utter your belief and see what people think of them.

IMO, that is a very poor way. If you state a false belief to the wrong person they will think it is a great idea and correct.

The best way to learn physics is to work problems. That is how any expert on these forums gained their expertise.

ZapperZ

Quote by DaleSpam

IMO, that is a very poor way. If you state a false belief to the wrong person they will think it is a great idea and correct.

Not only that. The tactic of spewing anything just so one gets other people to say what's wrong with it is a common practice of crackpots. See #16 on Are You A Quack?

To me, that is a LAZY way to learn, even if one is sincere.

Zz.

micromass

Quote by g.lemaitre

Ultimately however a student can read A and B and falsely conclude C. Of course under rare occasions the student can read D and find out that C is false, but those occasions take time and are rare. And of course it is also the case that a student will believe C and one expert will say that C is true and another will say C is false but fortunately those situations are in the minority. Nevertheless, it is also true that the best way to liberate yourself from false belief is to utter your belief and see what people think of them. That's why I'm here trying to get my beliefs on energy straight.

I have decided however that my real area of misunderstanding is a false interpretation of HUP and the Law of Conservation of Momentum, which is why I have a thread open at the QM forum. I more or less consider this thread resolved.

If you don't understand something, then there are two ways to learn. You can ask your question to experts and they will answer it. Now you have learned the answer to your question.
On the other hand, you can also search for the answer yourself. Read through various sources. Do problems. Do a simulation. Then you will have learned the answer to your question, but you will also have learned how to resolve misunderstandings. Being able to read a text and being able to understand it the correct way is a useful skill. If we just spoonfeed you the answers, then you will never learn this.

*Popper*

Quote by Vanadium 50

Don't put words in my mouth.

You didn't answer my question. Exactly how much more valuable do you think your time is than ours?

I know nobody asked me this question but if there were to I'd say that everyone's time is equally valuable regardless of who they are.

Similar discussions for: Force and Energy
Thread	Forum	Replies
Force to Potential Energy to Force again gives wrong formula	Classical Physics	4
force in kinetic energy/force in momentum =1	Introductory Physics Homework	2
Force And Energy	Introductory Physics Homework	3
Force and Energy	Introductory Physics Homework	1
Need some force/energy help	General Physics	2

Vanadium 50 Mentor	Easier for you. Not easier for the experts whose patience you are testing. This is why we discourage this mode of behavior. And just out of curiosity, exactly how much more valuable do you think your time is than ours?