Debunking the idea the earth accelerates upward

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Re: Debunking the idea the earth accelerates upward
« Reply #180 on: August 25, 2016, 11:52:37 AM »
Can you count the number of false assumptions you made in that??

Go on - ill give you time to check it :-)

Absolutely none.
Otherwise please point them out to me.
And I do mean point out any unreasonnable assumption, not any assumption at all.
Else you're basically asking me to describe the wavefunction of every quark in the ball AND resolve a quantic N body problem, and even one of them is impossible.


Wrong

Anyway, I am going to make a video of this simple (although obviously not simple to you) equation.

I will post it here :-)

I am not typing it all out on a smart phone - but keep checking in, you might (will) learn something.


p.s. There is also a conceptual argument you are missing here involving the effect of an accelerating earth on air resistance. 

Good luck :-)
« Last Edit: August 25, 2016, 11:54:24 AM by Physicsteacher »

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TotesReptilian

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Re: Debunking the idea the earth accelerates upward
« Reply #181 on: August 25, 2016, 11:55:02 AM »
Can you count the number of false assumptions you made in that??

Go on - ill give you time to check it :-)

ceciestuncompte is completely correct. This is why it is usually unwise to make fun of someone's intelligence. You never know when it will be your turn...

Also, what the heck is a SUVAT equation?

Edit: Also also, text is generally a lot more useful than videos when solving an equation for someone.

Re: Debunking the idea the earth accelerates upward
« Reply #182 on: August 25, 2016, 12:05:06 PM »
Can you count the number of false assumptions you made in that??

Go on - ill give you time to check it :-)

ceciestuncompte is completely correct. This is why it is usually unwise to make fun of someone's intelligence. You never know when it will be your turn...

Also, what the heck is a SUVAT equation?

Edit: Also also, text is generally a lot more useful than videos when solving an equation for someone.

He is not completely correct.

SUVAT equations are motion equations - probably exactly what you are used to but using UK terminology.

text might be good - but videos are easier for me to make :-)


Re: Debunking the idea the earth accelerates upward
« Reply #183 on: August 25, 2016, 04:58:13 PM »
Can you count the number of false assumptions you made in that??

Go on - ill give you time to check it :-)

Absolutely none.
Otherwise please point them out to me.
And I do mean point out any unreasonnable assumption, not any assumption at all.
Else you're basically asking me to describe the wavefunction of every quark in the ball AND resolve a quantic N body problem, and even one of them is impossible.


Wrong

Anyway, I am going to make a video of this simple (although obviously not simple to you) equation.

I will post it here :-)

I am not typing it all out on a smart phone - but keep checking in, you might (will) learn something.


p.s. There is also a conceptual argument you are missing here involving the effect of an accelerating earth on air resistance. 

Good luck :-)

I will admit I did not take in account the air resistance. Now instead of putting one equation after another, may I offer a general argument for why I do believe your entire point is moot ?
Just consider the referential of the earth.
If the earth is accelerating, both air and the ball can be studied in the referential of the earth by introducing a pseudoforce of value g directed to the ground - and you whole system is exactly equivalent to the case of gravity.

The only thing that will make the results differ is that if you throw the ball high enough, you will start to have to take into account the fact g is not a constant - but at that point that's probaly no longer a ball you're throwing, it's a cannonball. And as a matter of fact, this slight correction (that has to be done to the case of gravitation) can't possibly explain your point :

"So, when I throw a ball in the air, it takes the same time to go up as it does to come down. This is standard if the earth is not accelerating up.

However, due to the FE belief of acceleration of earth upward the ball would fall in a shorter time than it took to go up - but this doesnt happen"

Well I'm waiting for your video.

Re: Debunking the idea the earth accelerates upward
« Reply #184 on: August 25, 2016, 09:02:03 PM »
Can you count the number of false assumptions you made in that??

Go on - ill give you time to check it :-)

Absolutely none.
Otherwise please point them out to me.
And I do mean point out any unreasonnable assumption, not any assumption at all.
Else you're basically asking me to describe the wavefunction of every quark in the ball AND resolve a quantic N body problem, and even one of them is impossible.


Wrong

Anyway, I am going to make a video of this simple (although obviously not simple to you) equation.

I will post it here :-)

I am not typing it all out on a smart phone - but keep checking in, you might (will) learn something.


p.s. There is also a conceptual argument you are missing here involving the effect of an accelerating earth on air resistance. 

Good luck :-)

I will admit I did not take in account the air resistance. Now instead of putting one equation after another, may I offer a general argument for why I do believe your entire point is moot ?
Just consider the referential of the earth.
If the earth is accelerating, both air and the ball can be studied in the referential of the earth by introducing a pseudoforce of value g directed to the ground - and you whole system is exactly equivalent to the case of gravity.

The only thing that will make the results differ is that if you throw the ball high enough, you will start to have to take into account the fact g is not a constant - but at that point that's probaly no longer a ball you're throwing, it's a cannonball. And as a matter of fact, this slight correction (that has to be done to the case of gravitation) can't possibly explain your point :

"So, when I throw a ball in the air, it takes the same time to go up as it does to come down. This is standard if the earth is not accelerating up.

However, due to the FE belief of acceleration of earth upward the ball would fall in a shorter time than it took to go up - but this doesnt happen"

Well I'm waiting for your video.

Okay, I will type out the explanation for you ☺ I will spread it across a couple of posts because I'm not typing forever on my phone in one go in case it doesn't post properly.

Ready to learn?

Okay, so when a ball is thrown it appears to go up then down.

UA suggests in reality, it continues to just go up, but the earth catches it up.

During the up part, the ball travels faster than the earth, and the down part, the earth travels faster than the ball.

Let's treat these two parts as separate equations

See next post
« Last Edit: August 25, 2016, 09:26:30 PM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #185 on: August 25, 2016, 09:07:55 PM »
Now, let's take a ball that appears to be thrown say, 4m in the air.

For 4m it travels faster than the earth, and for 4m slower than the earth.

What UA says is that a when the ball is thrown the earth is "relatively stationary". In other words the speed of the ball is the speed of the earth, plus the speed the ball is given by the thrower.

We can therefore assume the relative starting speed of the earth here is zero (when compared to the measured speed of the ball on earth). This bit is important.

With me so far??
« Last Edit: August 25, 2016, 09:15:50 PM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #186 on: August 25, 2016, 09:12:49 PM »
Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)

https://sentynel.com/media/old/equations.html

Here is a link to these equations
« Last Edit: August 25, 2016, 09:27:34 PM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #187 on: August 25, 2016, 09:25:10 PM »
Here S = distance
T = time
A = acceleration
U = initial starting speed of the earth (not ball, which is where you cocked up)


So, how long does it take the earth to travel those first 4m?? In other words, bow long does it take for the ball to go up??

Well according to the equation I gave you in the last post (where U is zero remember)

T squared = 4/(0 + 1/2 9.8 )


This gives a time of......0.81s for T squared

So T = 0.9s

Remember, this is the time taken for the ball to rise

« Last Edit: August 25, 2016, 09:28:08 PM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #188 on: August 25, 2016, 09:31:45 PM »
Now, when calculating the time taken for the ball to fall (or the earth to travel the second 4m), we have to realise one important thing..
Lthe earth is now travelling faster. We cannot use zero for U anymore.

The earth has gained 9.8 x 0.9 m/s (acceleration x time).

In other words the earth is faster than it was (which is what UA depends on)


In fact it is 8.82 m/s faster

Re: Debunking the idea the earth accelerates upward
« Reply #189 on: August 25, 2016, 09:37:23 PM »
Let's put that into our equation to see how long it takes the ball to appear to fall...

T squared = S/(UT + 1/2A)

here the new value for U is 8.82, and T (in the brackets, which is the time the earth continued to accelerate over as the ball appeared to rise) is 0.9

The T in the bracket cannot be confused with the T in front of the = This is the time taken for the ball to fall.

So

Here T squared = 4/(8.82 x0.9 + 1/2 x 9.8 )

T squared = 0.31

Therefore T = 0.55s

« Last Edit: August 26, 2016, 12:53:40 AM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #190 on: August 25, 2016, 09:39:45 PM »
So there you have it.

Basic physics shows a ball thrown 4m in the air will take 0.9s to rise, and 0.55s to fall.

So, like I said, it falls faster than it rises.

Thanks and goodnight ☺

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Ski

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Re: Debunking the idea the earth accelerates upward
« Reply #191 on: August 25, 2016, 10:07:47 PM »
Hahahahaha

"Never think you can turn over any old falsehood without a terrible squirming of the horrid little population that dwells under it." -O.W. Holmes "Truth forever on the scaffold, Wrong forever on the throne.."

Re: Debunking the idea the earth accelerates upward
« Reply #192 on: August 25, 2016, 10:10:58 PM »
I am a retard who couldn't understand that

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Ski

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Re: Debunking the idea the earth accelerates upward
« Reply #193 on: August 25, 2016, 10:12:21 PM »
We can therefore assume the relative starting speed of the earth here is zero (when compared to the measured speed of the ball on earth). This bit is important.

Very important  lol


The best part is that you are so convinced you're right while you haughtily abase us and masquerade as a physics teacher...
« Last Edit: August 25, 2016, 10:28:15 PM by Ski »
"Never think you can turn over any old falsehood without a terrible squirming of the horrid little population that dwells under it." -O.W. Holmes "Truth forever on the scaffold, Wrong forever on the throne.."

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TotesReptilian

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Re: Debunking the idea the earth accelerates upward
« Reply #194 on: August 25, 2016, 11:07:36 PM »
Ugh. Dude, please tell me you aren't actually a physics teacher. This is super cringey.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)

Algebra is wrong.

T2 = 2(S - UT)/A.

Doesn't matter though. Read on.

Here S = distance
T = time
A = acceleration
U = initial starting speed of the earth (not ball, which is where you cocked up)

Be careful defining your terms. Make sure you get the directions consistent.

S = distance between the earth and the ball. S is positive when the ball is ahead of the earth. (Sball - Searth)
V = velocity between the earth and the ball. V is positive when the ball is faster than the earth. (Vball - Vearth)
A = acceleration between the earth and the ball. A is positive when the ball is accelerating faster than the earth. (Aball - Aearth)
U = initial velocity between earth and ball. Initially positive and greater than zero, because the ball is moving faster than the earth.

You can't immediately solve for T, because you don't know U yet. First solve for U, which happens to be 8.82 m/s by sheer luck. (Symmetry, actually.)

Now you can solve for T:

4 = 8.82T - 1/2AT2

Using the quadratic formula gives your original value for T, 0.9 seconds, again due to pure luck. (Hurray for symmetry!)

Let's put that into our equation to see how long it takes the ball to appear to fall...

T squared = S/(UT + 1/2A)

here the new value for U is 8.82, and T (the T in the brackets) is 0.9

No no no no no!!!! You can not arbitrarily decide that each T is different. They are both the same variable. They are the same value. Right now the relative velocity between the ball and the earth is zero. The distance is negative this time.

S = UT + 1/2AT2
-4 = (0)T + 1/2(-9.8)T2

Solving for T gives, once again, 0.9 seconds. The exact same answer as before.

Also, you mentioned air resistance, but didn't include it in your calculations. What gives?
« Last Edit: August 25, 2016, 11:12:04 PM by TotesReptilian »

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Ski

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Re: Debunking the idea the earth accelerates upward
« Reply #195 on: August 25, 2016, 11:27:08 PM »
Ugh. Dude, please tell me you aren't actually a physics teacher. This is super cringey

No no no no no!!!! You can not arbitrarily decide that each T is different. They are both the same variable. They are the same value.

Curse you and your arbitrary "rules". Don't you know he's better than you?


Quote from: hoppy link=topic=67716.msg1812063#msg1812063
You sir are a self righteous bore... You are no better than us despite your thoughts to the contrary.

Yes, I am far better.

Why?

Because I push people to be the best they can be, to think, question, reason and solve problems based on logic.

I push people to stand on the shoulders of the giants before them and contribute in a positive way to the world.

So yes, I am far better than you

Quote from: least educated round earther
I would say the leasrpt educated round earther, is more intelligent than the most educated flat earther.
Well, it doesn't seem so in this case now, does it?



I admire your patience, TR. I was going to let him twist in the wind a bit before going through the actual maths, but it's just as well.
« Last Edit: August 25, 2016, 11:32:53 PM by Ski »
"Never think you can turn over any old falsehood without a terrible squirming of the horrid little population that dwells under it." -O.W. Holmes "Truth forever on the scaffold, Wrong forever on the throne.."

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TotesReptilian

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Re: Debunking the idea the earth accelerates upward
« Reply #196 on: August 25, 2016, 11:47:46 PM »
I admire your patience, TR. I was going to let him twist in the wind a bit before going through the actual maths, but it's just as well.

Sorry to ruin your entertainment. You never know, he might come back and continue arguing for his version.

?

fliggs

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Re: Debunking the idea the earth accelerates upward
« Reply #197 on: August 26, 2016, 12:17:34 AM »
I admire your patience, TR. I was going to let him twist in the wind a bit before going through the actual maths, but it's just as well.

Sorry to ruin your entertainment. You never know, he might come back and continue arguing for his version.

Yes, he made an error in his maths. Of course, no one has ever done that before, right? But following his posts for some weeks now, he has schooled the rest of you clowns repeatedly in every topic. He clearly knows his stuff while you flat-earthers demonstrate nothing more than a tenacious adherance to a religious doctrine that is actively debunked at every turn. In fact, the flat earth is perhaps the easiest and most completely debunked idea in history.  Unicorns and fairies have more evidence.

Re: Debunking the idea the earth accelerates upward
« Reply #198 on: August 26, 2016, 12:38:42 AM »
Quote from: Physicsteacher link=topearth?
515.msg1813520#msg1813520 date=1472184475
We can therefore assume the relative starting speed of the earth here is zero (when compared to the measured speed of the ball on earth). This bit is important.

Very important  lol


The best part is that you are so convinced you're right while you haughtily abase us and masquerade as a physics teacher...

When I say relative I obviously mean if we are measuring the speed of the ball a xm/s, then it is xm/s faster than the earth.

Try to pick me up on the maths if you can understand it.

See, this is a pattern with you. I notice you do it to lots of people. You ignore post content and try to find unimportant spelling or grammatical error etc etc

You never explain anything, and when pressed you run away.

Like you will again now...I'm watching

1) explain the problem with the maths (u can't, its perfect)
2) explain (for the 15th time of asking) how vectors cause different measurements of g on earth
« Last Edit: August 26, 2016, 12:55:30 AM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #199 on: August 26, 2016, 12:43:13 AM »
Ugh. Dude, please tell me you aren't actually a physics teacher. This is super cringey.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)

Algebra is wrong.

T2 = 2(S - UT)/A.

Doesn't matter though. Read on.

Here S = distance
T = time
A = acceleration
U = initial starting speed of the earth (not ball, which is where you cocked up)

Be careful defining your terms. Make sure you get the directions consistent.

S = distance between the earth and the ball. S is positive when the ball is ahead of the earth. (Sball - Searth)
V = velocity between the earth and the ball. V is positive when the ball is faster than the earth. (Vball - Vearth)
A = acceleration between the earth and the ball. A is positive when the ball is accelerating faster than the earth. (Aball - Aearth)
U = initial velocity between earth and ball. Initially positive and greater than zero, because the ball is moving faster than the earth.

You can't immediately solve for T, because you don't know U yet. First solve for U, which happens to be 8.82 m/s by sheer luck. (Symmetry, actually.)

Now you can solve for T:

4 = 8.82T - 1/2AT2

Using the quadratic formula gives your original value for T, 0.9 seconds, again due to pure luck. (Hurray for symmetry!)

Let's put that into our equation to see how long it takes the ball to appear to fall...

T squared = S/(UT + 1/2A)

here the new value for U is 8.82, and T (the T in the brackets) is 0.9

No no no no no!!!! You can not arbitrarily decide that each T is different. They are both the same variable. They are the same value. Right now the relative velocity between the ball and the earth is zero. The distance is negative this time.

S = UT + 1/2AT2
-4 = (0)T + 1/2(-9.8)T2

Solving for T gives, once again, 0.9 seconds. The exact same answer as before.

Also, you mentioned air resistance, but didn't include it in your calculations. What gives?

Total reptilian you have totally cocked up 😇 (that's my smug face).

The algebra is not wrong.  The T are two different terms which I clearly stated in the text - you cannot use one to cancel the other. There is no factorising needed, you really made a mess here 😇. This is real physics - I get that you are trying but.... Come on, its not that hard, just read the text.

The T in the bracket was the time taken for the ball to rise. This was needed to find the new speed of earth when multiplied by acceleration - again this was explained. I stated in the first post the up and down parts would be treated separately.

The T on the left side, was the time taken for the ball to fall. These are two different measurement. My only error here was not using a lower case T for one of them (out I'm on my phone and it auto corrected)

All u prove here is you didn't read/follow the explanation.

The maths is perfect
Now, knowing the meaning of the two Ts, check again.

Its bulletproof.


I'd ask ski to check but I honestly don't think she has a clue, so I won't.
« Last Edit: August 26, 2016, 01:00:49 AM by Physicsteacher »

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fliggs

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Re: Debunking the idea the earth accelerates upward
« Reply #200 on: August 26, 2016, 12:48:05 AM »
its been a while since school but you wrote.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)


if you rearrange that you actually get
tsquared=2(S-UT)/A

correct me if I am wrong.

Re: Debunking the idea the earth accelerates upward
« Reply #201 on: August 26, 2016, 12:49:54 AM »
its been a while since school but you wrote.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)


if you rearrange that you actually get
tsquared=2(S-UT)/A

correct me if I am wrong.

Don't worry, they fucked up. Like I posted at the same time you did, the meaning of the two T are different. They can't cancel.

Its bulletproof 😇

I have edited the explanation part to this in reply 189 so its more idiot proof (which I guess it needs to be)
« Last Edit: August 26, 2016, 12:56:58 AM by Physicsteacher »

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TotesReptilian

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Re: Debunking the idea the earth accelerates upward
« Reply #202 on: August 26, 2016, 01:08:40 AM »
I admire your patience, TR. I was going to let him twist in the wind a bit before going through the actual maths, but it's just as well.

Sorry to ruin your entertainment. You never know, he might come back and continue arguing for his version.

Yes, he made an error in his maths. Of course, no one has ever done that before, right? But following his posts for some weeks now, he has schooled the rest of you clowns repeatedly in every topic. He clearly knows his stuff while you flat-earthers demonstrate nothing more than a tenacious adherance to a religious doctrine that is actively debunked at every turn. In fact, the flat earth is perhaps the easiest and most completely debunked idea in history.  Unicorns and fairies have more evidence.

I don't mind math mistakes. I make them myself quite often. His arrogance and insults are what bother me.

Also, I'm not a flat earther.

?

fliggs

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Re: Debunking the idea the earth accelerates upward
« Reply #203 on: August 26, 2016, 01:17:20 AM »
I admire your patience, TR. I was going to let him twist in the wind a bit before going through the actual maths, but it's just as well.

Sorry to ruin your entertainment. You never know, he might come back and continue arguing for his version.

Yes, he made an error in his maths. Of course, no one has ever done that before, right? But following his posts for some weeks now, he has schooled the rest of you clowns repeatedly in every topic. He clearly knows his stuff while you flat-earthers demonstrate nothing more than a tenacious adherance to a religious doctrine that is actively debunked at every turn. In fact, the flat earth is perhaps the easiest and most completely debunked idea in history.  Unicorns and fairies have more evidence.

I don't mind math mistakes. I make them myself quite often. His arrogance and insults are what bother me.

Also, I'm not a flat earther.

its not really arrogance at all. He is very good at what he does and his posts are very clear, very precise and yet met with the true insanity of the flat-earthers. What you mistake for arrogance is the repeated demonstration that FEers are wrong - all the time. And by huge margins.

Re: Debunking the idea the earth accelerates upward
« Reply #204 on: August 26, 2016, 01:19:30 AM »
I admire your patience, TR. I was going to let him twist in the wind a bit before going through the actual maths, but it's just as well.

Sorry to ruin your entertainment. You never know, he might come back and continue arguing for his version.

Yes, he made an error in his maths. Of course, no one has ever done that before, right? But following his posts for some weeks now, he has schooled the rest of you clowns repeatedly in every topic. He clearly knows his stuff while you flat-earthers demonstrate nothing more than a tenacious adherance to a religious doctrine that is actively debunked at every turn. In fact, the flat earth is perhaps the easiest and most completely debunked idea in history.  Unicorns and fairies have more evidence.

I don't mind math mistakes. I make them myself quite often. His arrogance and insults are what bother me.

Also, I'm not a flat earther.

Thanks Fliggs 😇

Reptilian - I notice you're not criticising the maths now. Well done for actually READING it.

And you are a fine one to talk about arrogance. Yesterday you didn't even know what SUVAT was, and then you try (and fail horribly) to correct me on it.  What a joke!

Told you, bulletproof ☺
« Last Edit: August 26, 2016, 01:21:55 AM by Physicsteacher »

Re: Debunking the idea the earth accelerates upward
« Reply #205 on: August 26, 2016, 01:23:01 AM »
Stillbat least you had the courage to reply. Ski will do what she always does and pretend not to read this

Hahaha

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TotesReptilian

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Re: Debunking the idea the earth accelerates upward
« Reply #206 on: August 26, 2016, 01:27:32 AM »
its been a while since school but you wrote.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)


if you rearrange that you actually get
tsquared=2(S-UT)/A

correct me if I am wrong.

Don't worry, they fucked up. Like I posted at the same time you did, the meaning of the two T are different. They can't cancel.

Its bulletproof 😇

I have edited the explanation part to this in reply 189 so its more idiot proof (which I guess it needs to be)

This is middle school level algebra and high school level physics dude. It should not be this hard. Tell you what, to prove that both T's must be the same, I'll derive your kinematic equation for you. How is your calculus?

position = x(t)
velocity = v(t) = dx/dt
acceleration = a(t) = dv/dt

We'll start with the equation for acceleration.

dv/dt = a(t)
dv = a(t) dt

Integrate both sides. Assume acceleration is constant.

∫dv = ∫a dt
v(t) = a t + v0

Now sub in the equation for velocity.

dx/dt = a t + v0
∫dx = ∫(a t + v0) dt
x(t) = a t2 + v0 t + x0

Now sub in S for the change in distance (x(t) - x0)

S = a t2 + v0 t

This is the "SUVAT" equation that you were using. Notice that we started out with a single time variable (t). All t's that arose from the integration are the same time variable.

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TotesReptilian

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Re: Debunking the idea the earth accelerates upward
« Reply #207 on: August 26, 2016, 01:30:33 AM »
Reptilian - I notice you're not criticising the maths now. Well done for actually READING it.

Went to get something to eat. Then I typed up a response. Chill pill.

Quote
And you are a fine one to talk about arrogance. Yesterday you didn't even know what SUVAT was, and then you try (and fail horribly) to correct me on it.  What a joke!

Told you, bulletproof ☺

*eyeroll*

Re: Debunking the idea the earth accelerates upward
« Reply #208 on: August 26, 2016, 01:36:34 AM »
its been a while since school but you wrote.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)


if you rearrange that you actually get
tsquared=2(S-UT)/A

correct me if I am wrong.

Don't worry, they fucked up. Like I posted at the same time you did, the meaning of the two T are different. They can't cancel.

Its bulletproof 😇

I have edited the explanation part to this in reply 189 so its more idiot proof (which I guess it needs to be)

This is middle school level algebra and high school level physics dude. It should not be this hard. Tell you what, to prove that both T's must be the same, I'll derive your kinematic equation for you. How is your calculus?

position = x(t)
velocity = v(t) = dx/dt
acceleration = a(t) = dv/dt

We'll start with the equation for acceleration.

dv/dt = a(t)
dv = a(t) dt

Integrate both sides. Assume acceleration is constant.

∫dv = ∫a dt
v(t) = a t + v0

Now sub in the equation for velocity.

dx/dt = a t + v0
∫dx = ∫(a t + v0) dt
x(t) = a t2 + v0 t + x0

Now sub in S for the change in distance (x(t) - x0)

S = a t2 + v0 t

This is the "SUVAT" equation that you were using. Notice that we started out with a single time variable (t). All t's that arose from the integration are the same time variable.

Oh my god you cant b this dumb!!

Read the dam thing

Re: Debunking the idea the earth accelerates upward
« Reply #209 on: August 26, 2016, 01:45:11 AM »
Ugh. Dude, please tell me you aren't actually a physics teacher. This is super cringey.

Now the SUVAT equation we will use is S = UT + 1/2AT SQUARED (I can't do superscript from my phone)

Let's rearrange to get time...?
This gives

T squared = S/(UT +1/2A)

Algebra is wrong.

T2 = 2(S - UT)/A.

Doesn't matter though. Read on.

Here S = distance
T = time
A = acceleration
U = initial starting speed of the earth (not ball, which is where you cocked up)

Be careful defining your terms. Make sure you get the directions consistent.

S = distance between the earth and the ball. S is positive when the ball is ahead of the earth. (Sball - Searth)
V = velocity between the earth and the ball. V is positive when the ball is faster than the earth. (Vball - Vearth)
A = acceleration between the earth and the ball. A is positive when the ball is accelerating faster than the earth. (Aball - Aearth)
U = initial velocity between earth and ball. Initially positive and greater than zero, because the ball is moving faster than the earth.

You can't immediately solve for T, because you don't know U yet. First solve for U, which happens to be 8.82 m/s by sheer luck. (Symmetry, actually.)

Now you can solve for T:

4 = 8.82T - 1/2AT2

Using the quadratic formula gives your original value for T, 0.9 seconds, again due to pure luck. (Hurray for symmetry!)

Let's put that into our equation to see how long it takes the ball to appear to fall...

T squared = S/(UT + 1/2A)

here the new value for U is 8.82, and T (the T in the brackets) is 0.9

No no no no no!!!! You can not arbitrarily decide that each T is different. They are both the same variable. They are the same value. Right now the relative velocity between the ball and the earth is zero. The distance is negative this time.

S = UT + 1/2AT2
-4 = (0)T + 1/2(-9.8)T2

Solving for T gives, once again, 0.9 seconds. The exact same answer as before.

Also, you mentioned air resistance, but didn't include it in your calculations. What gives?

Oh and you dont need to worry about signs here do you.

This is basically 2 equations to find the time taken for the earth to move 2 sets of 4 meters.

Everything is positive for both
However your model works if we factor that gravity is the force of acceleration ;-)

Thanks for that one ;-)
« Last Edit: August 26, 2016, 01:47:24 AM by Physicsteacher »