## Friday, June 24, 2011

### "It's A Simple Matter Of Physics!"

Damn right!

I read with a bit of amusement at this report out of New Zealand. It appears from my understanding that there was quick a debate on a "forward throw" in rugby as stated in one of the "rules", I think.

Now, I can't quite understand what the brouhaha is all about. However, it appears that people are puzzling on how a person who is running forward, then makes a pass backward, can result in a ball that is still moving "forward". Note that all of this description (forward, backward) implicitly implies a motion relative to ground and in reference to a particular direction.

What I gather from the report is that a lot of people didn't learn about a simple Galilean transformation.

"Basically it's got to be going backwards from the player, faster than the player is running forwards," said professor Matthew Collett, who teaches theoretical physics at the University of Auckland.

"So if the player throws the ball backwards and throws it slower than the speed he is running at, then relative to the ground, the pass will be going forward."

It really is simple physics! And who would have thought that Galilean transformation would be an issue in rugby?

Zz.

#### 1 comment:

Canticle said...

It's called a forward pass, or a 'knock on.'
It can be a major issue when the Kiwi team visit Europe as they seem to think it's the inertial frame of the passer and receiver that matters not the (rest) frame of the pitch!
Inertial frame transition is also a major issue in rugby, particularly when tackled head on!
And the inertial mass of the tackled player is entirely subject to the state of motion of the observer (tackler).
Which of course means that e = mc^2 is not equivalent to M = E/c^2, as the first is rest mass and the latter can only be inertial mass. So much for maths then!

Peter