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Old 08-14-2015, 05:33 PM   #101
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Ever notice that the Solar system is kind of like an atom? The Sun being the nucleus and the planets being electrons. Maybe our Solar system is actually one atom that's part of a molecule that's part of a single cell that makes up the tissue on a giant dog's nose.
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Old 08-14-2015, 05:36 PM   #102
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Sorry, how are you finding the tensile force of the string exactly? Magic string? Length of string, mass of die, angle of string gives me everything I need without some super string. I can add the gravitational force, the fake force and get the string force.

This is the entire point of fake force. You break down an unknown force (string in this case) into two component 90 degree forces. One of those is known and the fake force is then easier to find than the string force.
You can't find "the fake force" in the world of a static equilibrium. You don't need the length of the string for anything, by the way. The angle is totally sufficient. Unless you are hooking up a scale to the spring to read the tension and you know what the string is made of and want to take into account the elasticity absorbing some of the force.
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Old 08-14-2015, 05:36 PM   #103
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Old 08-14-2015, 05:39 PM   #104
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You can't find "the fake force" in the world of a static equilibrium. You don't need the length of the string for anything, by the way. The angle is totally sufficient. Unless you are hooking up a scale to the spring to read the tension and you know what the string is made of and want to take into account the elasticity absorbing some of the force.
OK so you don't understand what i wrote. Tell me your plan of finding the string force without first finding fake force.


What information do you need and explain your methodology.
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Old 08-14-2015, 05:45 PM   #105
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OK so you don't understand what i wrote. Tell me your plan of finding the string force without first finding fake force.


What information do you need and explain your methodology.
We're arguing different things. I'm arguing from the "you don't know the acceleration, your reference point is inside the car, what do you do" standpoint. You're arguing from the "you dont know the tension, your reference point is inside the car, what do you do" standpoint. In my case, I can find the tensile force (by hooking up a scale to the string) and use it to determine the acceleration. That's kind of a real world scenario for you. In your case, you know the acceleration (how? gyroscope I guess) and you're trying to find the tensile force and we assume you're not gonna hook anything up to the string.
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Old 08-14-2015, 05:55 PM   #106
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We're arguing different things. I'm arguing from the "you don't know the acceleration, your reference point is inside the car, what do you do" standpoint. You're arguing from the "you dont know the tension, your reference point is inside the car, what do you do" standpoint. In my case, I can find the tensile force (by hooking up a scale to the string) and use it to determine the acceleration. That's kind of a real world scenario for you. In your case, you know the acceleration (how? gyroscope I guess) and you're trying to find the tensile force and we assume you're not gonna hook anything up to the string.
You are skipping that step and knowing the string force with instrumentation and angle. This gives you the fake force as the string force is the combined opposite of the fake force and gravitational force.

What you don't understand is that if you find fake force and you know the mass of dice you can find the acceleration which is assumed to be horizontal.
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Old 08-14-2015, 06:04 PM   #107
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You are skipping that step and knowing the string force with instrumentation and angle. This gives you the fake force as the string force is the combined opposite of the fake force and gravitational force.

What you don't understand is that if you find fake force and you know the mass of dice you can find the acceleration which is assumed to be horizontal.
You can't just "find the fake force"! You have to know the acceleration of the reference frame to get it.
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Old 08-14-2015, 06:07 PM   #108
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You can't just "find the fake force"! You have to know the acceleration of the reference frame to get it.
Let me walk you through this step by step. Do you agree the fake force and the gravitational force vectors are perpendicular and combine to become the exact opposite of the string force?
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Old 08-14-2015, 06:21 PM   #109
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Let me walk you through this step by step. Do you agree the fake force and the gravitational force vectors are perpendicular and combine to become the exact opposite of the string force?
Are you at least measuring the angle of the string? So far you've said nothing about that, but if you do take the angle then of course you can find the acceleration of the vehicle without finding the magnitude of the tension in the string.
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Old 08-14-2015, 06:32 PM   #110
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Thats what i meant by "move back". The inertia is acting on the dice, putting tension on the srring. Would the tensionon the string not have been caused by inertial force?
No not in the slightest because inertial force doesn't really exist. The extra tension is created by the car accelerating. If you were traveling at a gazillion mph but not accelerating the dice would hang straight down. But since the car is accelerating and string cannot resist a bending moment the string is at the angle required to pull the dice forward and accelerate the dice at the same rate that the car is accelerating.
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Old 08-14-2015, 06:35 PM   #111
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Are you at least measuring the angle of the string? So far you've said nothing about that, but if you do take the angle then of course you can find the acceleration of the vehicle without finding the magnitude of the tension in the string.
I did say I needed the angle and the mass dude.


If you have angle and mass of die you can find fake force (or the horizontal component of the string force) and then use THAT to find the acceleration. You kept saying you CANNOT FIND THE FAKE FORCE but finding the horizontal component of the string force is the path to finding acceleration with the givens of mass of dice and angle of string. Simple. Fake force is used to break a complicated force into two component force vectors.
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Old 08-14-2015, 06:41 PM   #112
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No not in the slightest because inertial force doesn't really exist. The extra tension is created by the car accelerating. If you were traveling at a gazillion mph but not accelerating the dice would hang straight down. But since the car is accelerating and string cannot resist a bending moment the string is at the angle required to pull the dice forward and accelerate the dice at the same rate that the car is accelerating.
^^^Yes this. ^^^

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T is the tension of the string and is broken up into T sin θ as the horizontal component and T cos θ as vertical. T sinθ is the opposite of the fake force, T cos θ is the opposite of gravitational forces. If "you were traveling at a gazillion mph" T would be equal to T cos θ and T sin θ = 0


"Fake Force" is just the opposite of the horizontal component of the string force (T sin θ).
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Old 08-14-2015, 06:50 PM   #113
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Wouldn't letting go of the throttle, midlean, cause a sudden deceleration?
That would likely lead to increasing lean angle and turn radius, maybe lowside...

Unless you had a throttle lock to hold steady throttle, but you'd have to have some pretty big to lock the throttle while dragging a knee.
Yeah ive seen people crash because of letting off the throttle completely, my engine braking is reduced on the bike. Idk... ill take baby steps and see if I can do it. I think I could.
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Old 08-14-2015, 06:51 PM   #114
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Yeah ive seen people crash because of letting off the throttle completely, my engine braking is reduced on the bike. Idk... ill take baby steps and see if I can do it. I think I could.
Absolutely you can, but it's gonna do exactly what it does when you chop the throttle in a turn. If you anticipate that and you have enough , you can definitely get a good picture out of it.
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Old 08-14-2015, 07:10 PM   #115
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Old 08-14-2015, 07:16 PM   #116
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Old 08-14-2015, 07:19 PM   #117
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Holy , you guys can argue.

Yes, the story was simplified, because not everybody who rides a motorcycle is a physicist, or even took physics in school. There is really something to be said about being able to explain a topic to your grandmother - it's a talent that not many possess. I possess this talent, and that's what made me such a great chemistry and geochem tutor - being able to make people understand a difficult subject.

Of course it's going to be misleading to those who know and understand physics, because so much is not accounted for, but really, who cares?

It was fun to read. It was well done. It was understandable to the masses (?).

Good for you for knowing too much and making sure everybody else knows that you know more than we thought you knew.
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Old 08-14-2015, 07:20 PM   #118
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I seriously don't think any professor will use the term "fake force" unless they are talking to 2 year olds.
Imagine, for a moment, your average motorcycle rider...
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Old 08-14-2015, 07:29 PM   #119
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I seriously don't think any professor will use the term "fake force" unless they are talking to 2 year olds.
You would be wrong in your thinking.
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Old 08-14-2015, 07:32 PM   #120
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