Offline Action80

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Re: FE and ICBMs
« Reply #360 on: July 15, 2021, 10:21:08 AM »
You can describe the distance travelled in a given time frame for any moving body (whether its accelerating or not) by multiplying its avg velocity by the time. No one disputed this.

But that figure offers zero predictive powers for the instantaneous velocity at any time. For this discussion, AVERAGE VELOCITY FOR THE BURN PHASE IS A MEANINGLESS VALUE.

Please stop repeating this nonsense.

RIP to what started as an interesting thread.
Considering you are the one offering nonsense (a strawman, in other words) that has nothing to do with the incorrect figures offered by AATW (i.e., why a calculation of average velocity over the first five minutes of the flight clearly demonstrating a final velocity of 16,000 km/h at t+5 is not possible), then I will return the favor and ask you to stop repeating the strawman.
AVERAGE VELOCITY FOR THE BURN PHASE IS A MEANINGLESS VALUE.
Correct.
Incorrect.
« Last Edit: July 15, 2021, 11:14:50 AM by Action80 »

Offline Action80

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Re: FE and ICBMs
« Reply #361 on: July 15, 2021, 10:32:02 AM »
Acceleration for a race car is certainly not constant, yet average velocity over the course (also not linear) is expressed as defining the winner.
Yes, it's almost as if they can take the total approximate distance the car has driven, and then divide that number by the amount of time it took the driver to run the course. That is, notably, different than how you're coming up with the (wrong) average velocity in your own example. Do you see the difference?
Of course. That is why I was first in this thread to offer the d=rt solution, using five minutes for t and 250km for d, equaling 3000km/h. As far as your objection to the other calculation of average velocity = final velocity+initial velocity/2, well, you will just need to take that up with physicists and the other "sciency" dudes. Cause it is just as legit and it clearly demonstrates AATW's figures to be totally bogus.
An interesting real-world example to share.

Quote from: https://www.autosport.com/f1/news/how-fast-is-an-f1-car-top-speeds-of-f1-indycar-motogp-and-more-4980734/4980734/
Aerie Luyendyk averaged 236.986mph (381.391km/h) in qualifying for the Indy 500 in 1996, with his four-lap time of 2m31.908s still unmatched today.

That car, like all race cars, starts out at 0km/h. By lackey-math, that means it must have finished the race at 762.79km/h in order to achieve the record-holding average velocity of 381.391km/h. So lackey, can you show us evidence that IndyCars regularly finish races at velocities greater than 700km/h? That seems like a hard thing to just take on faith.
Since you are demonstrating extreme ignorance concerning how an average velocity of a four lap qualifying velocity, or even an average velocity of a whole race, is actually calculated, I doubt you should remain in the conversation any longer.

I will offer you a clue. The average velocity calculation for the four lap qualifier does not, should not, or would not ever include a value of 0 in its calculation. Of course, the average velocity over the entire race would include some 0 velocity figures (dependent on pit stops, wrecks, etc.), but even that calculation would not start with a 0 velocity figure.

Amazingly, your strawmanning was all accomplished much faster than the rocket we are discussing.

boydster, once you come to grips with all this, then come back. Until then, have a great day.
« Last Edit: July 15, 2021, 12:38:11 PM by Action80 »

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Offline Clyde Frog

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Re: FE and ICBMs
« Reply #362 on: July 15, 2021, 12:38:43 PM »
The car is starting at 0km/h. What speed is it going when it crosses the finish line? I'd like to plug those 2 values into your calculator and see what it comes up with for average velocity. It'll definitely be very accurate, right?

Offline Action80

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Re: FE and ICBMs
« Reply #363 on: July 15, 2021, 12:39:41 PM »
The car is starting at 0km/h. What speed is it going when it crosses the finish line? I'd like to plug those 2 values into your calculator and see what it comes up with for average velocity. It'll definitely be very accurate, right?
The car is not starting at 0 km/h in either four lap qualifying or the actual race.

Have you ever watched auto racing?

Go home, boydster. I think timmy is asking for your presence elsewhere.
« Last Edit: July 15, 2021, 12:42:29 PM by Action80 »

Re: FE and ICBMs
« Reply #364 on: July 15, 2021, 01:02:48 PM »
A Formula 1 race starts when the red lights go out, not when the car starts moving.  If a car is moving when the red lights go out, it is disqualified. 

Its velocity at the start is zero. 

Re: FE and ICBMs
« Reply #365 on: July 15, 2021, 01:54:56 PM »
A Formula 1 race starts when the red lights go out, not when the car starts moving.  If a car is moving when the red lights go out, it is disqualified. 

Its velocity at the start is zero.
I guess once it's finished the race and comes to a halt then its velocity at the end is also 0.
Therefore it's average velocity throughout the race must be 0, according to Lackey's calculator.
I wonder if anyone can spot the flaw in that argument.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

Offline Action80

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Re: FE and ICBMs
« Reply #366 on: July 15, 2021, 03:18:16 PM »
A Formula 1 race starts when the red lights go out, not when the car starts moving.  If a car is moving when the red lights go out, it is disqualified. 

Its velocity at the start is zero.
That is correct for Formula One, which was not the example discussed prior to this.

Offline Action80

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Re: FE and ICBMs
« Reply #367 on: July 15, 2021, 03:24:22 PM »
A Formula 1 race starts when the red lights go out, not when the car starts moving.  If a car is moving when the red lights go out, it is disqualified. 

Its velocity at the start is zero.
I guess once it's finished the race and comes to a halt then its velocity at the end is also 0.
Therefore it's average velocity throughout the race must be 0, according to Lackey's calculator.
I wonder if anyone can spot the flaw in that argument.
Yeah, I am sure they can spot the flaw.

As usual, it is your gaslighting the issue.

The actual end of the race is what is called crossing the FINISH LINE with the required amount of displacement "under your belt" so to speak.

The official declaration of the end of the race does not include the process of bringing the car or other cars to a halt.

Re: FE and ICBMs
« Reply #368 on: July 15, 2021, 03:53:27 PM »
As far as your objection to the other calculation of average velocity = final velocity+initial velocity/2, well, you will just need to take that up with physicists and the other "sciency" dudes. Cause it is just as legit and it clearly demonstrates AATW's figures to be totally bogus.
It is legit IF the rate of acceleration is constant. Which is not the case with rockets or in the examples which have been worked through with you.
Is your entire problem with all of this that you work out the average velocity one way and get 3,000 and you do it another way and get 8,000 and you don't understand why you get two different figures? Reason is what I keep telling you. The 8,000 figure is only valid if the rate of acceleration is constant. It is not constant for rockets, which is how a rocket could end up going 250km in 5 minutes and end up with a final velocity of 16,000. I literally broke that down minute by minute with an example of how that could happen.

But none of this really matters because...

AVERAGE VELOCITY FOR THE BURN PHASE IS A MEANINGLESS VALUE.

Your entire response to that was "Incorrect". Why is it incorrect?
IF the rocket is going at 16,000km/h and is at 250km altitude when the engines shut down then that's all you need to know to calculate the maximum altitude it will reach (well, you need to know the mass and radius of earth too so you can take into account how g varies as the rocket ascends - that is the complex part). The average velocity or acceleration before the point of engine shut down has absolutely no bearing on the answer.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

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Offline Clyde Frog

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Re: FE and ICBMs
« Reply #369 on: July 15, 2021, 04:01:25 PM »
A Formula 1 race starts when the red lights go out, not when the car starts moving.  If a car is moving when the red lights go out, it is disqualified. 

Its velocity at the start is zero.
That is correct for Formula One, which was not the example discussed prior to this.
Fine. I'm not a fan of racing, I'll concede I didn't know IndyCar begins with the cars moving. That doesn't matter much, we could just as easily talk about a race where the cars start at 0mph and finish at however fast they are going when they cross the finish line - I guess that'd be Formula 1, based on DD's post? The point of the thought experiment is to show that your method of finding an average velocity is hopelessly flawed.

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Offline Iceman

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Re: FE and ICBMs
« Reply #370 on: July 15, 2021, 04:03:14 PM »
Two identical cars sit on a flat road. One is travelling at a constant speed of 8000 km/h. As soon at it passes car 2, car 2 hits the gas and continues accelerating. Both cars travel for 5 minutes, car 1 at a constant 8000km/h, car 2 accelrating to a final velocity of 16000 km/h, before both take their feet off the gas at the same time and just coast, allowing friction to gradually slow them down.

They both have the same avg velocity for the 5 minute trip, but if we want to know if one of them will travel further before it comes to a comlete stop,

Average
velocity
doesnt
matter.


Offline Action80

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Re: FE and ICBMs
« Reply #371 on: July 15, 2021, 04:22:42 PM »
As far as your objection to the other calculation of average velocity = final velocity+initial velocity/2, well, you will just need to take that up with physicists and the other "sciency" dudes. Cause it is just as legit and it clearly demonstrates AATW's figures to be totally bogus.
It is legit IF the rate of acceleration is constant. Which is not the case with rockets or in the examples which have been worked through with you.
Is your entire problem with all of this that you work out the average velocity one way and get 3,000 and you do it another way and get 8,000 and you don't understand why you get two different figures? Reason is what I keep telling you. The 8,000 figure is only valid if the rate of acceleration is constant. It is not constant for rockets, which is how a rocket could end up going 250km in 5 minutes and end up with a final velocity of 16,000. I literally broke that down minute by minute with an example of how that could happen.

But none of this really matters because...

AVERAGE VELOCITY FOR THE BURN PHASE IS A MEANINGLESS VALUE.

Your entire response to that was "Incorrect". Why is it incorrect?
IF the rocket is going at 16,000km/h and is at 250km altitude when the engines shut down then that's all you need to know to calculate the maximum altitude it will reach (well, you need to know the mass and radius of earth too so you can take into account how g varies as the rocket ascends - that is the complex part). The average velocity or acceleration before the point of engine shut down has absolutely no bearing on the answer.
For the final time, any figures relating to acceleration do not interject themselves into calculations regarding average velocity.

You contributions and assertions they somehow do are patently false.

Re: FE and ICBMs
« Reply #372 on: July 15, 2021, 08:34:18 PM »
For the final time, any figures relating to acceleration do not interject themselves into calculations regarding average velocity.

You contributions and assertions they somehow do are patently false.

http://hyperphysics.phy-astr.gsu.edu/hbase/avari.html

Quote
Note that even in this one-dimensional case for non-constant acceleration, the average velocity is not equal to the average of the initial and final velocities.

The average velocity expression from the constant acceleration equations works only for constant acceleration where the graph of velocity as a function of time is a straight line, the average being the midpoint of that line over the chosen time interval

Apology accepted.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

Offline Action80

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Re: FE and ICBMs
« Reply #373 on: July 16, 2021, 11:56:08 AM »
For the final time, any figures relating to acceleration do not interject themselves into calculations regarding average velocity.

You contributions and assertions they somehow do are patently false.

http://hyperphysics.phy-astr.gsu.edu/hbase/avari.html

Quote
Note that even in this one-dimensional case for non-constant acceleration, the average velocity is not equal to the average of the initial and final velocities.

The average velocity expression from the constant acceleration equations works only for constant acceleration where the graph of velocity as a function of time is a straight line, the average being the midpoint of that line over the chosen time interval

Apology accepted.
And as previously acknowledged elsewhere in this thread, the velocity profile in the case of this particular, given a time frame of five minute burn, varies so little from the vertical, an average velocity figure derived via calculus would not fit a 5 minute flight achieving 250km.

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Offline Iceman

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Re: FE and ICBMs
« Reply #374 on: July 16, 2021, 01:07:53 PM »
velocity profile

You keep using that word. I do not think it means what you think it means.

Offline Action80

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Re: FE and ICBMs
« Reply #375 on: July 16, 2021, 01:12:12 PM »
velocity profile

You keep using that word. I do not think it means what you think it means.
And you keep using "that word," when you call out what is, quite obviously, TWO WORDS.

Have a nice day.

Re: FE and ICBMs
« Reply #376 on: July 16, 2021, 01:51:22 PM »
velocity profile

You keep using that word. I do not think it means what you think it means.
Inconceivable!

Anyway...the average velocity or the "velocity profile" are completely irrelevant here. The only things that matter are the altitude and velocity at the time of engine shutdown, and the strength of earth's gravitational field. With those things you can work out the maximum altitude of the rocket. And by "you" I mean someone who is better at math than me. Over to you, Lackey. I'm looking forward to seeing your workings.
"On a very clear and chilly day it is possible to see Lighthouse Beach from Lovers Point and vice versa...Upon looking into the telescope I can see children running in and out of the water, splashing and playing. I can see people sun bathing at the shore
- An excerpt from the account of the Bishop Experiment. My emphasis

Re: FE and ICBMs
« Reply #377 on: July 16, 2021, 02:10:20 PM »

And you keep using "that word," when you call out what is, quite obviously, TWO WORDS.

Have a nice day.


Since we're not advancing the argument at this stage, I think you quite obviously mean "..... what are, quite obviously, TWO WORDS". 

Anywho; Has everyone heard of "muzzle velocity".  Its the key parameter in the ballistics of firearms and artillery.  Nothing to do with rates of acceleration.   Nothing to do with average speed in the barrel. 

Muzzle velocity.  The instantaneous speed at the end of burn. 

Offline Action80

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Re: FE and ICBMs
« Reply #378 on: July 16, 2021, 03:16:58 PM »
Yeah, speed at the end of the burn, which happens to be in the scenario discussed here, t+5.

Working with a displacement of 250km at t+5.

Yielding, according to d=rt, an average velocity of 3,000 km/h.

If a man made rocket could even travel at a velocity of 16,000 km/h (I doubt it could), and did reach that speed at the very end of 5 minutes of burn, it blows either the distance traveled figure or the yielded rate of velocity figure out of the water and puts a nail in the coffin of this BS fiction pushed by warmongers.

No wonder you guys don't come up with your supposed saving grace of calculus to supply the average rate of velocity for the profile.

You know it is closer to the 8000 km/h average figure yielded by linear calculation.
« Last Edit: July 16, 2021, 04:03:58 PM by Action80 »

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Offline Iceman

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Re: FE and ICBMs
« Reply #379 on: July 16, 2021, 04:40:21 PM »
supply the average rate of velocity for the profile.

I beg your pardon?