Mathematical equations, physics buffs.

Iggypoppin' · 15-04-2011, 08:16 PM

I said I'd start one!

general maths problems, equations, formulae, discussion on maths education methods, etc.
Physics equations, space time theories, Einstein etc. There's got to be some people interested and educated in this stuff. Graphs and other instruments encouraged to be posted!
For the record, there isn't a treadmill big enough, and if there was I think there are some people who would argue that friction would prohibit the plane from taking off.

gtfpv · 15-04-2011, 08:18 PM

anyone who thinks the plane wont take off better not post in this thread ,OK?

buggo · 15-04-2011, 08:44 PM

??? So if a planes going 300km/h on a treadmill, but 0km/h +- wind, earth rotation, relative to Earths surface, atmosphere, etc, it will take off ??? Can't see it happening, unless I have the wrong idea...

SEZ213 · 15-04-2011, 09:03 PM

Quote:

Originally Posted by Iggypoppin'

I said I'd start one!

general maths problems, equations, formulae, discussion on maths education methods, etc.
Physics equations, space time theories, Einstein etc. There's got to be some people interested and educated in this stuff. Graphs and other instruments encouraged to be posted!
For the record, there isn't a treadmill big enough, and if there was I think there are some people who would argue that friction would prohibit the plane from taking off.

Well, you started this thread...what's the first question...

Iggypoppin' · 15-04-2011, 09:15 PM

Solve for x

8(3/9)/.002([4xG]pi x 9)
--------- =x
T^3(Gx4)/5

where G is gravity acting on how lazy I am, pi is PI as in the number 3.14 etc, and T is me not caring anymore but given a numerical value. Which is also unknown.

In Focus · 15-04-2011, 10:01 PM

If you're starship is travelling at the speed of light, what happens when you turn on the headlights?

shedcoupe · 15-04-2011, 10:04 PM

Quote:

Originally Posted by Iggypoppin'

Solve for x

8(3/9)/.002([4xG]pi x 9)
--------- =x
T^3(Gx4)/5

where G is gravity acting on how lazy I am, pi is PI as in the number 3.14 etc, and T is me not caring anymore but given a numerical value. Which is also unknown.

Well, assuming that G = 9.8 m/s² and pi = 3.142, and T = obviously it must be zero, then the answer is : x = 'with a chicken'.

Iggypoppin' · 15-04-2011, 10:38 PM

Quote:

Originally Posted by In Focus

If you're starship is travelling at the speed of light, what happens when you turn on the headlights?

The light will get to x before you do. X being the destination and light being faster than I could actually travel, I will allow the possibility that I am travelling at 185,000m/ps(mps=miles per second) speed of light is 186,000mps, so the light from the headlights will reach x before I do.

SEZ213 · 15-04-2011, 10:45 PM

Quote:

Originally Posted by shedcoupe

Well, assuming that G = 9.8 m/s² and pi = 3.142, and T = obviously it must be zero, then the answer is : x = 'with a chicken'.

I got a duck...

shedcoupe · 15-04-2011, 10:49 PM

Quote:

Originally Posted by Sezzy

I got a duck...

You forgot to carry the goose and add the first number you thought of .....

LXL15 · 15-04-2011, 10:51 PM

You're not alone, I love this stuff. I just have nothing to say except I love New Scientist. Nerdy? Yes, very

loud and proud...

Ibrox90 · 15-04-2011, 11:07 PM

Lol you can spot the Australian School of Mathematics and Science School students a MILE away lol naish

flappist · 15-04-2011, 11:13 PM

Quote:

Originally Posted by buggo_gt

??? So if a planes going 300km/h on a treadmill, but 0km/h +- wind, earth rotation, relative to Earths surface, atmosphere, etc, it will take off ??? Can't see it happening, unless I have the wrong idea...

You have the wrong idea.

Aircraft do not accellerate due to power being applies to the wheels, the accellerate because they push against the air.

Once the air flows fast enough to create a pressure differential between the top and bottom of the wing greater than the mass of the aircraft it will move upwards.

If the air is moving slower relative to the ground than the plane it will move up and forward, if the same it will just move up and if greater it will move up and backwards BUT IT WILL ALWAYS TAKE OFF

flappist · 15-04-2011, 11:22 PM

Quote:

Originally Posted by In Focus

If you're starship is travelling at the speed of light, what happens when you turn on the headlights?

Well the headlights are also travelling at the speed of light so relative to the starship they just work normally but relative to you depending on your reference point they may appear to do many different things. They won't ACTUALLY do different things just look like they are.

It is all about reference.

You are on the side of the road.
A car drives past at 100km/h with the horn blowing.
The frequency of the horn changes as it goes past but the driver does not hear any difference.

Did the horn change or not change?

**GasoLane** · 15-04-2011, 11:26 PM

Quote:

Originally Posted by flappist

Aircraft do not accellerate due to power being applies to the wheels, the accellerate because they push against the air.

Once the air flows fast enough to create a pressure differential between the top and bottom of the wing greater than the mass of the aircraft it will move upwards.

If the air is moving slower relative to the ground than the plane it will move up and forward, if the same it will just move up and if greater it will move up and backwards BUT IT WILL ALWAYS TAKE OFF

Would that be like an old Tiger Moth with a top speed of about 60mph and flying into a 60mph headwind.

It's flying, but not getting very far?

grandpa_spec_F6 · 15-04-2011, 11:30 PM

Quote:

Originally Posted by flappist

You have the wrong idea.

Aircraft do not accellerate due to power being applies to the wheels, the accellerate because they push against the air.

Right you are, this hypothetical also wouldn't work as there must be a force applied to the wings (wind) to generate lift, thus allowing to gain altitude. .

Iggypoppin' · 15-04-2011, 11:31 PM

Quote:

Originally Posted by flappist

Well the headlights are also travelling at the speed of light so relative to the starship they just work normally but relative to you depending on your reference point they may appear to do many different things. They won't ACTUALLY do different things just look like they are.

It is all about reference.

You are on the side of the road.
A car drives past at 100km/h with the horn blowing.
The frequency of the horn changes as it goes past but the driver does not hear any difference.

Did the horn change or not change?

physics own laws defy this question. As only light can travel at the speed of light, the question can't be applicable and thus I can alter it how I wish

anyone want to help me pierce space time with a gravity drive and travel to proxima centauri?

**GasoLane** · 15-04-2011, 11:32 PM

Quote:

Originally Posted by flappist

You are on the side of the road.
A car drives past at 100km/h with the horn blowing.
The frequency of the horn changes as it goes past but the driver does not hear any difference.

Did the horn change or not change?

Oh-Oh... I can see Schrodinger's cat making an appearance (or not) soon

grandpa_spec_F6 · 15-04-2011, 11:32 PM

Quote:

Originally Posted by IggyPoppin'

physics own laws defy this question. As only light can travel at the speed of light, the question can't be applicable and thus I can alter it how I wish
anyone want to help me pierce space time with a gravity drive and travel to proxima centauri?

No...

grandpa_spec_F6 · 15-04-2011, 11:33 PM

Quote:

Originally Posted by GasOLane

Oh-Oh... I can see Schrodinger's cat making an appearance (or not) soon

That may or may not happen in a either a near or distant future depending on the independant variables... and if the coins fall out of the watermelon, altogether, in the end, between naps.

Work Horse · 15-04-2011, 11:37 PM

Oldie but a goodie

a = 1, b = 1

a = b
a^2 = b^2
a^2 - b^2 = 0
(a-b)(a+b) = 0
(a-b)(a+b)/(a-b) = 0/(a-b)
1(a+b) = 0
(a+b) = 0
1 + 1 = 0
2 = 0
1 = 0
1 + 1 = 1

Rodp · 15-04-2011, 11:41 PM

Quote:

Originally Posted by buggo_gt

??? So if a planes going 300km/h on a treadmill, but 0km/h +- wind, earth rotation, relative to Earths surface, atmosphere, etc, it will take off ??? Can't see it happening, unless I have the wrong idea...

Mythbusters created a treadmill large enough to test a small plane - it took off.

The thrust is not provided by driving wheels, the wheels are inconsequential beyond minimising friction between the ground. The thrust is generated via air being propelled by propeller, jet or <insert Area 51 tech here>

Iggypoppin' · 15-04-2011, 11:48 PM

Quote:

Originally Posted by Work Horse

Oldie but a goodie

a = 1, b = 1

a = b
a^2 = b^2
a^2 - b^2 = 0
(a-b)(a+b) = 0
(a-b)(a+b)/(a-b) = 0/(a-b)
1(a+b) = 0
(a+b) = 0
1 + 1 = 0
2 = 0
1 = 0
1 + 1 = 1

If 1=0 then how does 1+1=1?? shouldn't it be 1+1=0?

SEZ213 · 15-04-2011, 11:50 PM

Quote:

Originally Posted by Iggypoppin'

If 1=0 then how does 1+1=1?? shouldn't it be 1+1=0?

1+1= a window...everyone knows that

flappist · 15-04-2011, 11:51 PM

Quote:

Originally Posted by GasOLane

Would that be like an old Tiger Moth with a top speed of about 60mph and flying into a 60mph headwind.

It's flying, but not getting very far?

A person I know was once flying a Piper Tomahawk near melbourne during a 50 knot wind. He could not land as the stall speed of the aircraft was less than that and he was actually being blown backwards up the runway.

He had to waste time orbiting until there was a slight drop in wind speed and then did a flapless dive at the deck with several other pilots running out to shove blocks of wood on the wings to break up the lift so they could drag it off and tie it down.

Iggypoppin' · 16-04-2011, 12:02 AM

where 1=0
1+1= 0
because
1=0
so
0=0
1+1=0
why is this relevant if everything is 0 and all we are doing is multiplying or dividing by 0???

SteveJH · 16-04-2011, 12:20 AM

Quote:

Originally Posted by flappist

A person I know was once flying a Piper Tomahawk near melbourne during a 50 knot wind. He could not land as the stall speed of the aircraft was less than that and he was actually being blown backwards up the runway.

He had to waste time orbiting until there was a slight drop in wind speed and then did a flapless dive at the deck with several other pilots running out to shove blocks of wood on the wings to break up the lift so they could drag it off and tie it down.

If the runway was long enough could he have just landed with the wind in that case rather then against it?

FGII-XR6 · 16-04-2011, 01:21 AM

Quote:

Originally Posted by buggo_gt

??? So if a planes going 300km/h on a treadmill, but 0km/h +- wind, earth rotation, relative to Earths surface, atmosphere, etc, it will take off ??? Can't see it happening, unless I have the wrong idea...

zero lift will be acheived as lift is caused by airspeed differential between the top and bottom of the airfoil creation a low pressure zone above the wing, the higher pressure below the wing then provides lift. aerodynamics 101

Iggypoppin' · 16-04-2011, 02:00 AM

I am still up and just wondering if anyone can explain vectors(as used in einsteins theory of relativity) without confusing me too much. I have a basic physics background so you can use nice big words and some equations and I won't derp at them.

Swordsman88 · 16-04-2011, 02:13 AM

I've seen that a=1 b=1 example before...its pretty obvious where the issue comes up because in the step 0/(a-b) leads to 0/0 and dividing by 0 brings up a world of issue that little trick ignores.... Still looks funny though...

Quote:

Originally Posted by flappist

You have the wrong idea.

Aircraft do not accellerate due to power being applies to the wheels, the accellerate because they push against the air.

Once the air flows fast enough to create a pressure differential between the top and bottom of the wing greater than the mass of the aircraft it will move upwards.

If the air is moving slower relative to the ground than the plane it will move up and forward, if the same it will just move up and if greater it will move up and backwards BUT IT WILL ALWAYS TAKE OFF

The problem with this question is while what you say is perfectly true, 99% of people ignore the little chestnut of 'maximum tyre speed'. This fact came up in a debate on a airliner forum where some bright chap pointed out that the mythbusters test (which is the only case i know of where this fact was atcually tested on full scale) would work for any size scale. Well not if you look at an airliner it might not.

Case in point. A medium loaded B767-300 has a takeoff speed (v2) of 150knots (roughly), so call it 172 mph. So if you pull the conveyor belt along at 172mph but apply thrust for takeoff than the 767 will take off...but the wheel speed is 2 x 172mph....Problem. Maximum tyre speed for a 767 is perhaps 190mph. Certainly i dont' know of any airliner tyre with greater than 210mph before it pops.

So in that test you'd pop all your tyres pretty quick and then assuming the rims dug into your mystical converyor belt than the takeoff would most likely never happen. These sorts of things just play on your perceptions...look at it critically and it all comes out in the wash...