Tigers vs Quins

[northerntiger]

YBH you have a shaky grasp of physics. The 'scientific theory of gravity' (which is pretty well accepted as fact) pulls an object towards the earth ie downwards. Which is irrelevant to this argument.

[cidermark]

YBH you have a shaky grasp of physics. The 'scientific theory of gravity' (which is pretty well accepted as fact) pulls an object towards the earth ie downwards. Which is irrelevant to this argument.

Completely correct! No more relevant than introducing forward momentum as an excuse for the receiver of a pass to actually catch it in front of the passer.

[Old Hob]

Consider a train travelling at a constant 60mph. I hold my arm out of the window and I am holding a cricket ball. The ball is therefore travelling at 60mph to a stationary observer. I am joined by a train on a parallel track heading in the same direction. It is travelling at the same speed but the carriage windows on this second train line up one back from mine. This means the first window in their coach "A" is opposite the second window in my coach "A". Curiously enough, I am in the first window of coach "A" and my twin brother is staring out of the first window of coach "A" in the other train. I throw him the ball. It has clearly gone backwards. However, Yellow Balaclava Hunter, standing on the bridge at the station we are passing, sees the ball leave my hand and go forward to my brother's.
This is the argument.
A rugby ball carried by a runner has the momentum of that runner and will go forward until that momentum is dissipated. However, it will RELATIVELY go backwards.

Pip pip.

[cidermark]

Damn this is getting good!,,,

Yes, every motion is relative to a stationary body (except the cosmic speed of light and quantum physics).

The IRB (or whoever was in charge then) defined a forward pass as the ball leaving the player and travelling towards the opposition try line.

The try line therefore becomes the stationary observer.

If the ball is received closer to the oppositions try line than the position of the passer when they released it, then the ball must have been travelling in a forwards direction, relative to the stationary observer.

[Old Hob]

In that case Cidermark, all passes are forward passes except from stationary passers eg a scrum half from the base of a scrum would be legal.

[Granby]

Does the velocity at which it is passed back make a difference ? ie if greater than the forward velocity?

[cidermark]

In that case Cidermark, all passes are forward passes except from stationary passers eg a scrum half from the base of a scrum would be legal.

Not quite. You are assuming that the observer is the player passing the ball which is not the case in the IRBs definition of a forward pass.

All that is required is that, to the stationary observer (the try line), the ball doesn't get any closer to you before the receiver catches it.

[northerntiger]

Does the velocity at which it is passed back make a difference ? ie if greater than the forward velocity?

Yes it does. Also the speed at which the player is traveling when he passes the ball

[drc_007]

Consider a train travelling at a constant 60mph. I hold my arm out of the window and I am holding a cricket ball. The ball is therefore travelling at 60mph to a stationary observer. I am joined by a train on a parallel track heading in the same direction. It is travelling at the same speed but the carriage windows on this second train line up one back from mine. This means the first window in their coach "A" is opposite the second window in my coach "A". Curiously enough, I am in the first window of coach "A" and my twin brother is staring out of the first window of coach "A" in the other train. I throw him the ball. It has clearly gone backwards. However, Yellow Balaclava Hunter, standing on the bridge at the station we are passing, sees the ball leave my hand and go forward to my brother's.
This is the argument.
A rugby ball carried by a runner has the momentum of that runner and will go forward until that momentum is dissipated. However, it will RELATIVELY go backwards.

Pip pip.

It was really brought home to me when doing summer coaching on a pitch that had been freshly mown leaving stripes across the pitch. We had the players warming up doing a simple passing practice, I'd say that when the players are running at full speed, for the majority of passes the ball moves forward. It is only really apparent when there is a static frame of reference such as a line across the pitch.

[drc_007]

There is also a video

http://www.youtube.com/watch?v=RgMlDy2jP9s

[BJ.]

Do we need to take the rotation of the Earth and orientation of the pitch into consideration?

Welford Road is 52.59°N which equates to a rotational speed of approximately 1014.5kph. Since the pitch is east-west orientated, this means if a ball is carried at the same speed towards either end, it will have more forward momentum when heading towards the Goldsmith Stand end.

Just a thought.

[loretta]

Now we all know that the ball travels faster than a man running or this game of ours would be very dull indeed. Therefore, it should be possible to pass the ball at a speed that was greater than it's objective speed relative to the pitch. If the correct angle of pass was combined with a faster enough ball, it should be possible to deal with fact that the passer was moving forwards at the time.

Of course, this might be fairly tricky when both passing and receiving players are running forwards, so they would have to be quite good at it. You know, good enough to earn a living at it. Possibly even professionals!

[Johnnyg]

Consider a train travelling at a constant 60mph. I hold my arm out of the window and I am holding a cricket ball. The ball is therefore travelling at 60mph to a stationary observer. I am joined by a train on a parallel track heading in the same direction. It is travelling at the same speed but the carriage windows on this second train line up one back from mine. This means the first window in their coach "A" is opposite the second window in my coach "A". Curiously enough, I am in the first window of coach "A" and my twin brother is staring out of the first window of coach "A" in the other train. I throw him the ball. It has clearly gone backwards. However, Yellow Balaclava Hunter, standing on the bridge at the station we are passing, sees the ball leave my hand and go forward to my brother's.
This is the argument.
A rugby ball carried by a runner has the momentum of that runner and will go forward until that momentum is dissipated. However, it will RELATIVELY go backwards.

It really is that simple. YBH's argument ignores simple physics and would mean players would have to be running at least 10 metres behind the player from whom they receive the pass to ensure that although the ball had been passed backwards, it did not move forwards relative to the exact spot from which it was passed. Either that or the forward velocity of the runners would have to be reduced. It would be a slow and boring game. It would be very simple to defend against. Furthermore, to referee such an interpretation the pitch would need to have a grid of lines on it every metre or so. Imagine how often the crowd would shout forward pass if the ball moved 1 inch forward? It is of note that the only reason this whole debate arose was because of a line on the pitch, the numerous other passes in this match that were away from pitch lines went unnoticed because at speed they do not look forward to people accustomed to watching professional rugby; because they aren't!
In our pitch-gridded boring game almost every single pass in the build up to a try would have to be reviewed unless the player was chucking it so obviously backwards that there would be little prospect of any decent fast running tries anyway. Frankly what's wrong with the system we have?

[G.K]

Google Galilean Invariance.

I did this and could find no reference to TMOs re-inventing the laws of Rugby and Physics or any explanations regarding why Quins 10 was allowed to block Tigers 6 tackling the ball carrier

[BJ.]

Google Galilean Invariance.

Sounds more like the title of the next episode of The Big Bang Theory.