Tall lorries?

Further apologies for another follow-up to my own post but I think a bit of "in vino veritas" leads me to agree with you that a high CoG does have an influence which tends to reduce the risk of a lorry toppling in short gusts. This is on the basis that:

a. the wind speed which causes the lorry to tilt does not depend on the height of the CoG but

b. the _rate_ at which it tilts does, because a higher CoG gives a bigger moment of inertia and so means the net torque for a given wind gives a smaller angular acceleration, so

c. there is - other things being equal - more time for the wind speed to drop below the point where the lorry keeps on tilting before the lorry passes the tipping point.

Sorry I missed that.

The complicating factor is that other things aren't equal: the angle of the "tipping point" is, as you say, smaller for a higher CoG. I am not going to attempt to solve now which wins out when ;)

(none needed) ;-)

That's for considering my thoughts to be valid (I wasn't sure). ;-)

No, as you say, ITRW there are too many other variables to be able to predict too much accurately. ;-)

As a parallel to that, I had a habit of accidentally spoiling peoples 'surprise' presents when I felt them (though the wrapping paper).

So, daughter, thinking she would trick me, made up a present that looked like and was the exact same size, weight and feel as a Toblerone bar and gave it to me with the 'right, guess what this is then?'.

I held it and rotated it about it's centre and 'noticed' the turning moment was wrong, with most of the mass being in the middle, not spread along the entire length so I said 'It's not a Toblerone bar'. ;-)

Bless her, she had weighted a Toblerone bar and made up an exact equivalent weight with 2p pieces but stuck them all together in the

*middle* of the triangular box. ;-)

Cheers, T i m