# Where does a newton come from?

1. Jun 13, 2007

### bazz89

Hey, I'm new to this forums so I hope I'v posted this in the right section.

I'v just started my new job at a large engineering firm, and the chairman has posed a question to all his employee's which I was hoping you could help me with. His Question is as follow;

"Where does a newton come from and where does it go?"

For example, If I were to hit someone with a force of 1 newton, where did that netwon come from, and where did it go?

I don't think there is any definitive answer, but i would greatly appreciate your theories and input, cheers.

2. Jun 13, 2007

### G01

Uhh.....It came from your hand and went into whoever you hit?? Is this what your looking for, or something much more in depth. This is really a vague question.

3. Jun 13, 2007

### bazz89

Yeah, more in depth, sorry should have explained that. I was just using the punch as an example. He is wanting to know where newtons originate from, and where they go when they have been used.

4. Jun 13, 2007

### cepheid

Staff Emeritus
This question makes no sense. A newton is a unit of force, not a physical entity that appears and disappears.

5. Jun 13, 2007

### bazz89

Ok let me try to explain it again, i know its not a very clear question,

He tells us that engineering is all about controling newtons, he is very obssesed with newtons, he is trying to figure out where forces originated form, where forces first came to be, my answer was the big bang, but he is asking where they were before the big band? The force needed to create the big bang, where did this force come from? Does anybody have any idea's on pre-big bang in relation to forces?

6. Jun 13, 2007

### cepheid

Staff Emeritus
That's not how I would put it, but ok...

When you think about it, most of the forces encountered in engineering and everday life (e.g. contact forces) are electrostatic in nature. So the question of the origin of these forces is really the question(s)

what is electric charge?
why is matter the way it is?
or even, why is the universe the way it is?

The latest physical theories can put forward models of matter that explain its observed properties, but physics doesn't really attempt to answer why it is so. This is getting into the realm of the philosophical, so I'm not sure why the chairman of your *engineering* company is dwelling on this point.

I'm no cosmologist, but I think that the statement "before the big bang" is meaningless. Then again, my answer to his question would have been what I said just above, and not, "the forces came from the big bang."

7. Jun 13, 2007

### arildno

A newton, or amount of force if you like, measures the rate of energy transfer.

Thus, it is energy that gets shuffled back and forth, not forces as such.

8. Jun 13, 2007

### bazz89

ok thanks for your help, i'll see what he says on the matter

9. Jun 13, 2007

### cepheid

Staff Emeritus
I thought it measured the rate of momentum transfer?

Even so, you make a good point!

10. Jun 13, 2007

### arildno

Oh, dear. I am chagrined, embarassed, I shudder with shame and horror and self-loathing. It measures the rate of momentum transfer.

Now, I will go the bucket of water.

11. Jun 13, 2007

### chroot

Staff Emeritus
I'm rather embarrassed that any engineer, much less the owner of an engineering firm, would be publicly asking questions as meaningless and ill-formed as this one.

- Warren

12. Jun 13, 2007

### bazz89

yeah, i know. he seems to be the kind of engineer that would just take a hammer, or grinder to something that dosn't work though, lol

13. Jun 13, 2007

### chroot

Staff Emeritus
Well, all of the macroscopic forces human beings feel in every day life are the result of a single fundamental force: electromagnetism. We can quantify and analyze and describe this force to any level of detail you desire. We cannot now (or perhaps ever) explain why the universe includes this force. Physicists don't generally spend much time on these "why" questions, since we cannot answer them. You can always punt and just use the anthropic principle: if the universe were any other way, we wouldn't be here to discuss it.

- Warren

14. Jun 13, 2007

### Staff: Mentor

Yeah, I was just thinking - we're supposed to say that there's no such thing as a stupid question, but jeez, this one is pretty bad.

15. Jun 13, 2007

### G01

I want to believe that this chairman isn't an engineer, just because of this question.

16. Jun 13, 2007

### bazz89

yeah he used to be, ever heard of Score? its a firm that overhauls and repairs offshore oil and gas valves, they have also branched into overhauling gas generator turbines. he must be doing something right cause he staretd the company on his own about 25 years ago, now its worldwide and he's a multi-millionaire.

17. Jun 13, 2007

### nrqed

You would not include gravity as a macroscopic force human beings feel in every day? Just curious....

18. Jun 13, 2007

### chroot

Staff Emeritus
:rofl: Okay, true. I was thinking only in terms of people punching each other, but of course, you're right.

- Warren

19. Jun 13, 2007

### rcgldr

Since a newton is a force, it's not directly related to work or energy. You can apply a force (or a torque) without movement, so no work or change in energy occurs.

In the case of a force without movement, it's not going anywhere, it's not getting consumed, ... For example, a compressed spring in a vice. It takes work to initially compress the spring from a relaxed state, but once the movement stops, the spring and vice continue to apply forces to each other, but no work is being done, and no force is being consumed.

20. Jun 13, 2007

### Staff: Mentor

Well, what you "feel" of gravity is the floor pushing up on you and keeping you from falling through the earth, so it's still electrostatic repulsion.

21. Jun 14, 2007

### cepheid

Staff Emeritus
Yeah, but there are other ways to feel gravity in everyday life (like *falling* for example). I think nrqed's point that it should be included in the category of "forces experienced by humans on a macroscopic scale" is perfectly valid.

22. Jun 14, 2007

### Staff: Mentor

Do you feel gravity if you are falling...?

23. Jun 16, 2007

### cepheid

Staff Emeritus
Maybe not, but is it necessary to belabour this point when you know what I am trying to say? Unless it is your contention that gravity can never be felt in everyday life. What about when you are struggling to try to keep your balance? What about when you fail to do so, because your centre of gravity shifts in an unexpected way?

24. Jun 16, 2007

### jambaugh

Let me give it a try. Remember a Newton as a force is a rate of change of momentum. It is the momentum (newton-seconds=kg meters/sec) which is conserved (and thus must "come from somewhere" and "go somewhere").

You could in principle slap me with a million newtons but do it so quickly (for one quadrillionth of a second) that only one one-millionth of a newton-second is imparted to my face.
I wouldn't feel a thing.

Until you specify how long a period of time a newton is applied then nothing has been defined to have happened.

Usually when you see idealized impulsive forces which cause instantaneous changes in the path of a massive object the force (number of newtons) is formally infinite since the duration is infinitesimally small so that the impulse (change in momentum) is finite. This is an idealization where we don't care exactly how long the actual force was applied as long as it was only large for a short period of time.

This is also relates to the principle behind airbags, padded helmets, and other impact cushioning devices. They stretch out the time it takes for the user's momentum to change from whatever to zero. Thus they reduce the maximum force applied and keep bones from breaking and flesh from bruising (too much).

Regards,
James Baugh

25. Jun 16, 2007

### Astronuc

Staff Emeritus
I suppose we would need to differentiate between statics and dynamics.

Perhaps this guy is testing his engineers to see how they respond to questions, or perhaps he is waxing philosophical.

I would hope any engineer has some basic notion of where force arises.