Question of the day

BennyD

BennyD

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drewf said:
Not quite. As the ball falls it is following a ballistic orbital trajectory, and for an object with no other forces acting on it this will indeed be following the path that a great circle would describe. It will not be falling along a ground path on a line of latitude - in the northern hemisphere it will always turn to the south, and of course vice-versa in the southern hemisphere. A great circle can't be a line of latitude, except at the equator. All lines of longitude are great circles./QUOTE]

I still don't think that a ball falling vertically describes a great circle as it isn't passing between two points on the surface of a sphere. It's travelling down the plane of a great circle but, IMO, it's not passing along the arc. As I said, a great circle can be a line of latitude or longitude but, as you point out, there's more of one than the other!
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drewf

drewf

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BennyD said:
drewf said:
Not quite. As the ball falls it is following a ballistic orbital trajectory, and for an object with no other forces acting on it this will indeed be following the path that a great circle would describe. It will not be falling along a ground path on a line of latitude - in the northern hemisphere it will always turn to the south, and of course vice-versa in the southern hemisphere. A great circle can't be a line of latitude, except at the equator. All lines of longitude are great circles./QUOTE]

I still don't think that a ball falling vertically describes a great circle as it isn't passing between two points on the surface of a sphere. It's travelling down the plane of a great circle but, IMO, it's not passing along the arc. As I said, a great circle can be a line of latitude or longitude but, as you point out, there's more of one than the other!
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Sorry Ben - that's exactly what I meant. The ball "falling vertically" travels down the plane of a great circle. The ground track isn't a single point, nor a line of latitude, except at the equator, which also happens to be a great circle.
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Contigo

Contigo

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Deary me this is getting a tad silly now!

Next we will be debating the plane on the moving runway/conveyor belt!
 
BennyD

BennyD

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It may appear silly if you don't understand what's going on but Drew and I are having an enjoyable discussion on a higher plane. ;)
 
CatmanV2

CatmanV2

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BennyD said:
This seems to imply that the train does stop; two negatives making a positive and all that. Also the atmosphere moves at roughly the same speed as the earth otherwise it would be difficult to walk against 1000mph winds.
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Implication simply cannot trump observed evidence.

Imagine how many flies your plane goes through on a typical trip.

C
 
CatmanV2

CatmanV2

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48,943
Contigo said:
Deary me this is getting a tad silly now!

Next we will be debating the plane on the moving runway/conveyor belt!
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There really *really* is no debate about that. If your physics isn't up to it there's a thousand videos on Youtube. :)

C
 
spkennyuk

spkennyuk

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We are getting away from the Genisis of the thread. As educational as it is I shall pose a new question for the day for you all to wake up to.

Name the song and the Artist or band for the following lyrics :-

"She's got something you just can't trust
It's something mysterious
And now it seems I'm falling, falling for her"

Should be an nice easy one to start the ball falling again ! :)
 
CatmanV2

CatmanV2

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48,943
spkennyuk said:
We are getting away from the Genisis of the thread. As educational as it is I shall pose a new question for the day for you all to wake up to.

Name the song and the Artist or band for the following lyrics :-

"She's got something you just can't trust
It's something mysterious
And now it seems I'm falling, falling for her"

Should be an nice easy one to start the ball falling again ! :)
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Genesis: Invisible Touch.

C
 
davy83

davy83

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2,829
Sorry , i was busy missed all this stuff, I think you will find my answer is both correct and verifiable, whether you choose to see the subtle and interesting aspect of this question or not.

drewf said:
Sorry Davy, that's a myth. It's simply not true...

There's nothing in physics that will support your answer, unless the front of the train is made of similar material to the fly! In accelerating the fly through 95mph, no part of the train front has to decelerate to 0, not even for an instant.
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drewf

drewf

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7,159
davy83 said:
Sorry , i was busy missed all this stuff, I think you will find my answer is both correct and verifiable, whether you choose to see the subtle and interesting aspect of this question or not.
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I thought I'd explained the difference regarding energy and momentum between elastic and inelastic collisions? It's verifiable that the train does not at any time, no matter how brief and on what scale, have a velocity of zero.
 
drewf

drewf

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7,159
Question then:

What creates the loudest underwater sound, and how it is actually created? This happens all the time, every day - it's not an atomic explosion or similar.
 
BennyD

BennyD

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In the theoretical world I'm sure there is an argument for both viewpoints but in the real world, a 500 tonne train travelling at 90 mph will not decelerate to 0 and accelerate back to 90mph in mere fractions of a second no matter how many theories you bring to the party. If you hit the ground with an unopened parachute, you would take longer to stop and you certainly wouldn't get up without noticing it. ;)
 
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