Because we don't make up such a force. That is why.
‘Recall from chapter 5 that centrifugal force is an INERTIAL force exerted upon an object in a rotating frame of reference. In the context here, it arises from the centripetal acceleration of a Galilean moon traveling in essentially a circular orbit around Jupiter. To most pre-Newton thinkers, the centrifugal force acting on planets or satellites was a real one. Many of their arguments centered upon the nature of the force required to balance out the centripetal force. They completely missed the point that from the perspective of an inertial observer, the satellite was undergoing centripetal acceleration inward.
G. R. Fowles, and G. L. Cassiday, Analytical Mechanics Fifth Ed. P.184
The centrifugal force is not real. It is made up so that the motion of an object is correctly described in a non-inertial reference frame. Hence, when you use Newton’s law in a rotating frame of reference you must include it so they will be correct.
I'd say let's replicate your work. Then I'd look very carefully. In fact everything that I can reasonably think of doing has been done. See the next bit.
What would be done is exactly what has been done. The possibility of addition forces has been considered and the possibility of Newton's laws breaking down.
I’m sorry. I just don’t believe you. If you found it useful to postulate a new force you would, and bugger to whether Newton’s laws are correct or not.
quote:
Astronomers studied the Doppler shift of the radio signals to help calculate the distances of the probes. After extensive analysis, they dismissed instrumentation error, propellant leaks and minor heat emissions as causes of the negative thrust. "Perhaps the spacecraft inadvertently produced an unknown force that is not yet understood. Perhaps scientists will have to reconsider basic assumptions about the laws of physics. No one has come up with a conventional explanation. One possible reason is that it is a modification of gravity."
from:
http://www.geocities.com/solarstormmonitor/Pioneer.html
I’m not sure this says anything about considering Newton’s laws wrong. I don’t know what basic assumptions of physics he is talking about reconsidering. They seem to be considering abnormalities in gravitational theory.
Nieto has long been interested in the possibility that gravity works differently on antimatter than on the familiar matter that makes up our everyday world. This led him to consider how well we understand gravity's influence on normal matter and whether studies of the motions of comets or spacecraft could be used to identify any deviations from the expected influence of gravity.’
Now if over centuries the postualtion of a force when descrepancies were noted had always produced new interesting science and real discoveries, that is it was a useful thing to do, what would you think would be a good bet when the situation arose again. Right, postulate a force!
As I said before, if you found it useful to postulate a new force you would.
However, as you can see above, when the observations require change it is considered. And here they are considering pretty fundamental change.
I’m still not sure they are considering the overthrow of conservation of momentum.
However, would you through something out at the first moment of a discrepancy? Not until you have lots of good information. Science is conservative when it comes to well tested ideas.
I wouldn’t throw anything out if I found it useful.
Now, I think we've reached a point where you can see that Newton's laws can be tested.
No. You have only shown where you can test, at most, the predictions of Newton’s laws, which is exactly what I said to begin with. It’s verifiability is in its usefulness.
They aave actually been falsified in the case of relativity.
So in relativity, bodies at rest do not remain at rest unless acted upon by a force? Force is not equal to the rate of change of momentum? Forces exerted are not equal and opposite? The only thing wrong was Newton’s concept of momentum (and/or space and time, however you want to look at it). Once that is corrected Newton’s laws can be applied.
The possibility of significant change beyond postualting a new force has also been considered. Is there anything else that one could reasonably consider doing?
Sure. Chuck the theory and come up with a new one.
For a wide variety of conditions it has been tested and "proved".
It has only been proved by its usefulness.
The coreolis and centrifigal forces are frequently called "fictitious forces". They are convenient in allow an intuitive understanding of what goes on.
They are NECESSARY to describe the motion of a body in a non-inertial reference frame.
They are completely unnecessary if you want to do detailed classical mechanical calculations directly using Newton's laws.
Not if you apply them in a non-inertial reference frame.
Your problem with this hints that you aren't all that familiar with the physics.
You have got to be kidding.
Sorry, figure of speech. Any postulated additional force (or other effect) needs to be fitted into what is already known. It can not contradict well founded observations already made under other conditions.
You seem to be saying that any new postulated force has to allow Newton’s laws to correctly describe the motion of the object. Isn’t that the purpose of postulating the new force to begin with? So Newton’s laws predict the correct behaviour?
Thus, if the pioneer problem requires a modification to gravity then apples must still be predicted to fall.
Once again, why would we postulate a force that causes Newton’s laws to describe the motion incorrectly?
Obviously, one possibility is always experimental error. With something as well established as the laws of motion a single anomaly wouldn't result in an instant chucking of the whole thing.
What? You seem to be saying that just because an object accelerates there may not have been a force. It might be experimental error. Accelerations are caused by forces, not experimental errors (whatever that means).
Once error and other things have been ruled out then it gets very interesting. As an example see the Pioneer anomaly.
I still don’t think they are considering an overthrow of conservation of momentum.
Guess what, the images you are seeing on the screen are a result of those sources. Discovered well after the idea of charge was needed. You don't know the history of this very well do you?
All you seem to be saying is that if two objects exert forces on each other then the source of the force is the objects. Ok. My point is that if the known forces the objects exert on each other do not allow Newton’s laws to correctly describe the motion, then a new force between the objects is postulated.
And gee, amazing isn't it? When the additional force is postulated, mechanisms for it are found, it is measured and observed directly and when tests are done minimizing or removing it altogether then Newton's laws hold.
What mechanisms? The electric force was postulated to describe the motion some objects underwent. The property of charge was given to the objects such that the force between then was proportional to their respective charges. The mechanism was invented to describe the motion. You seem to act like Newton’s laws predicted charge.
This is obviously why only an idiot would object to trying the same trick the next time some discrepancy shows up. It has worked spectacularly well in the past. As you say, "Is it useful?"
Yes. Using forces to describe the motion of objects is very useful. So what?
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