Show Posts
This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.
I'm going out for an hour.
I'll answer any questions when I'm back
Any questions ?
Ok answer this little quizz then:
(Please don't use google, just answer from memory or with intuition.)
1) Quantum physics : Of which of the following mathematical or physical facts can one rigorously deduce the Hesienberg principle of incertitude ?
a) Wave functions have no well defined position.
b) Linear operators of a non-trivial linear space do not form a commutative ring.
c) Fourier transformation of real periodic functions yields infinite results (from which stems the necessity of using distributions).
d) Information can not travel faster than the speed of light.
e) It is impossible to measure position of elementary particles without disturbing them by interaction with the measuring equipment.
2) Optics : Why can't you use transmission electronic microscopy in bright field with a thick sample ? Why can you do so with an optic microscope ?
a) Because of shorter wavelength
b) Because of longer wavelength
c) Because of fundamental differences in the interaction with the sample
d) Because of chroma
e) Because of reflected light
3) Thermodynamics : What is the main reason why your coffee get cold faster when there is wind ?
a) Because the winds make your cofee move faster inside your cup.
b) Because of cold wind currents.
c) Because the wind makes the heating air up of your cup go away faster.
d) Because dioxygen reacts with carbon in the cofee.
e) Because winds make your cofee evaporate faster.
4) Statistical physics : What is the difference between bosons and fermions ?
a) They are not made of the same elementary particles.
b) The spin of bosons is of greater value than the spin of fermions.
c) They differ in their potential occupation numbers per elementary state .
d) Fermions interact with matter, bosons pass through it unaffected.
e) Bosons have no mass and can reach higher speed.
5) Electromagnetism : One of this phenomenon or physical law can not be deduced from Maxwell laws. Which one ?
a) Induction.
b) Ohm's law.
c) Capacitor charge.
d) Electro-magnets.
e) Kirchoff current law.
Enjoy !
Right
Let me guess what u will be picky with...
1) My phone autorotated the video, so it appears sideways. Just put up with it or don't watch it, I'm sure you can lock rotation on your phone to correct it.
2) At one point I say 9.8 x 1.4 is 14, but that's because I was actually multiplying 9.8 by 1.429. If you follow the video u will know why
Now let's see if you numpties can understand conceptual ideas and the proper use of maths.
Your whole problem is that you believe for some reason that S=10 meters in both case - which is an unsubtansiated claim, since you did not define S.
Your calculs show since the Earth travels faster in the second phase, it take less time to rise up 10 meters. Well, duh. We knew that.
Your problem is you do not define S properly.
If S is the distance travelled by the Earth, your calculations are correct but have nothing to do with the ball. Earth travels 10 meters =! ball rise 10 meters.
If S is the distance between the Earth and the ball, you fail to see that the ball is even moving. Nowhere in your calculations do the initial velocity of the ball appear. What you also fail to see is in that theory, when you believe the ball has risen up 10 meters in the air, it has actually risen more than that. Also again ball rising 10 meters up != earth rising 10 meters up.
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)
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
HA HA HA HA !
... Excuse me, but this was just too funny.
More seriously I will stop to make fun of you, and just explain why your math is wrong, IF you accept to read the posts of other and entertain the possibility of being wrong.
In the equation you tried to use ( s = (1/2)*a*tē + u*t ), s, a and u are the displacement, the acceleration and initial velocity of your system. If you want your system to be the ball, so be it. If you want your system to be the earth, that's strange but that's ok. However, you cannot say that it's both.
You said that u=0 and a = g =9,8, so your system is the earth. So what you have calculated is how much time it takes the earth to travel up by 4 meters. Are you still with me ?
But then you say "Remember, this is the time taken for the ball to rise". Except it's not. There is no rising ball at all in your system.
You did not even care to introduce the initial velocity of the ball, and still you expect it to rise. How ?
Ever try to throw a ball by letting it fall on the ground ?
It does not go up.
At all.
The time you calculated is how much time it takes for the earth to rise of 4 meters. Nothing more.
The idea that the ball will rise for 4 meters and then fall for 4 meters is proved nowhere in your post, nor do you care to explain if you mean distance with the Earth or absolute distance to the non accelerating referential.
Way to assume your result.
I mean, your whole post shows that you are using formulas that you obviously don't understand.
I'm not trying to make an appeal to authority, but have you even finished high school ? I just can't understand anyone with any sort of undergrad background in physics sprouting this nonsense, much less a pysic teacher.
Maths time!
s - displacement: the distance travelled by the object under question.
t - how much time passes in the situation under question
u - initial velocity of the object at starting point
v - velocity at end of time
a - acceleration of the object.
All this has been said already, I just want everything to be contained in one post for easy reading/reference.
So, let's throw a ball up with fixed speed u>0, where we model the Earth's starting velocity to be zero.
How long is it before the Earth's speed is u? In practise, this will be modelled by the top of the ball's arc, before it seems to begin descending.
Well, a=9.8, u=0, v=u, we want to find t.
Use the first SUVAT equation to find t = u/9.8
Now then, at this point, the Earth and the ball are travelling at the same speed, so it will seem as though the ball is stationary in the air. A moment before, it was ascending: a moment after, it's descending.
Unnecessary step, but fun:
The ball is still moving at speed u. As such, we run into Zeno's paradox: by the time the Earth catches up with it, the ball has still had a chance to move on a little further.
Let's look at how long it takes, from our starting point, for the Earth to catch up with the ball.
Using the fact the ball is not accelerating so a=0, we use our value of t and u=u, to note s=u2/9.8. This is how far it travels before the Earth's speed is the same as it.
(The Earth reaches that point in root(2) u^2/9.8 )
But when the Earth reaches that point, the ball's moved on. And when the Earth meets that point, the object's moved on...
An infinite sum clearly isn't the easiest way to solve this, but it easily gives us a way to check:
Let's see what happens when t = 2u/9.8. This is twice the time taken for the ball to reach the apex of its flight. We use the second equation.
The displacement of the ball is s=ut = 2u2/9.8
The displacement of the Earth, using the same equation, is s=0.5at2 = 2u2/9.8
They've both travelled the same distance, so the ball would in fact take the same amount of time to ascend as it does to descend.
The Earth's round, and there are a lot of issues with UA, but this isn't one of them. The flaws with your working have already been pointed out.
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
No. Up is positive. Down is negative. Or you can reverse them. As long as you are consistent. If I had made everything positive in the first equation, I would have gotten something besides 0.9 seconds.
I don't normally do this, but as a last ditch effort, I am going to try an appeal to authority. I have been studying mathematics for a very long time. I know a lot of mathematics. This is the type of thing I can do in my sleep. Please believe me.
If you still don't believe me, I'll have to let someone else handle it. Time for some sleep.
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?
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.
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 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.
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?
Quote from: Physicsteacher link=topearth?
515.msg1813520#msg1813520 date=1472184475We 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...
I am a retard who couldn't understand that
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.
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.
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.
I would say the leasrpt educated round earther, is more intelligent than the most educated flat earther.
This is because there is no evidence for a flat earth, so flat earthers are all stupid
Dude, why must you reinforce the stereotype that Ski is complaining about? Whether what you say is true or not, it doesn't help your argument.
who cares what ski is complaining about??? Are you her boyfriend??? No - but Ski is just another flat earther trying to spread stupidity to the vulnerable.
In my opinion, when I hear total B.S. it needs calling out on.
There is a difference between calling out BS when you see it, and making an unsupportable statement like "all flat earthers are dumber than all round earthers."
The purpose of the first is to stop the spread of ignorance. The purpose of the second is... something else. To hurt someones feelings? To make yourself feel superior? Whatever. Just my thoughts. Take it or leave it.
First off...
Sorry for the boyfriend comment. That was childish.
No worries.QuoteSecondly, I do believe that round earthers are more intelligent than flat earthers. Why? Well because the earth isn't flat, all the evidence points to a round earth - so to believe a flat earth, despite that, requires a very low intelligence level.
In general... let's just say I don't disagree. However, you made a pretty universal declaration that all flat earthers are less intelligent than all round earthers. There are a lot of really dumb people out there. Most of them probably believe the earth is round. Statistically speaking, your statement is almost guaranteed to be false.
