Math Is Fun Forum

Ah, thanks, Bob, that does ring a bell. My memory is not what it... sorry, what were we talking about?

Also, if an object is shown to have moved in the negative direction could that mean either it turned around and headed back towards its origin; or, it could have went into reverse (if it was a vehicle; or, I suppose, a person, etc, like Spike Milligan Walking Backwards for Christmas, for example).

Thanks, Bob.

Although when I Googled abscissa and ordinate the first few results said those were names for the x and y co-ordinates, not the axes themselves.

Thanks, Bob, thanks, Phil.

Having asked around I think I’ve got it now, and realise I should’ve included more information, and therefore context, with my question.

Khan was quite thorough with their notation. They showed various symbols and asked what each stands for and whether it was a vector or a scalar.
When they put x (for position) they had the little rightwards arrow above it, indicating a vector.
They also had an arrowed v, also indicating a vector.
And then they had a plain, unarrowed v, indicating, I think I see now, in this context, a scalar. Although someone pointed out that, strictly speaking, there should be vertical bars either side of this unarrowed v, to indicate absolute value, to indicate the magnitude alone of the velocity vector.

I’ve noticed in lots of maths questions (GCSE level) they keep it simple, e.g, no bar line above to indicate average rather than instantaneous; or no avg to indicate average; no arrows to indicate vectors; etc. I guess this makes sense given the context. It’s maths, not physics, even though it technically it is physics, if you know what I mean. And those letters (v, s, u, etc) could be any letters when the exercise is, for example, to show that you can change the subject of a formula.

Good points about the steering wheel and gas pedal, Phil

Thanks, KerimF

"Chocolate teapot

A chocolate teapot is an analogy for any useless item; a teapot made from chocolate would melt, and be impossible to use.

Experimental researchers in 2001 did indeed fail to successfully use a chocolate teapot they had made. Later research, however, by The Naked Scientists in 2008, showed that such a teapot could be used to make tea, provided that the walls of the teapot were more than one centimetre thick."

Question. What  if you took your chocolate teapot up a mountain where water boils at less than 100 degrees C?

Thanks, Bob.
A student on Khan Academy said it was a scalar, likening it to 6ft tall. That made me think of volume, where the depth would be a scalar, yes? Length, breadth(depth), and height are scalars, yes?
But I also, like you, thought of the deep part as directional, deep translating to down.
But when I thought of down as a direction I thought of south. But when digging down (I thought of a grave) we’re not going south are we, not in the conventional sense at least?
Anyway. I then imagined a treasure map. Walk 30 feet west. Then dig down 6 feet. Could we represent this on an x,y co-ordinate grid, x being east/west, y being up down (I suppose up could apply to the treasure being up a tree, or on a hillside?). What about north/south though? Would we need an x,y,z grid if north/south was also involved?
Nb; Is the ‘down’ in ‘dig down’ superfluous? We can’t dig up! I suppose we could dig at an angle as opposed to straight down, but that would still be down, yeah?
In a nutshell; does it depend on context, whether 6ft deep is a scalar or a vector? If the context is volume, it’s a scalar? If the context is firing arrows upwards from a trench, or digging for treasure, it’s a vector?

Thanks, Bob.
All obvious, doh!
I think the new terms had me overthinking it. Vectors. Scalars. Sounded complicated. And velocity, which I’d always thought of as a fancy word for speed, not being quite the same as speed.
Your lion example reminded me of the old one; Two guys on safari spot a lion. One takes his Nike Sprints out of his backpack, starts putting them on. The other says, “You’ll never outrun a lion.” The first says, “No, but I’ll outrun you.”

Sorry, Phil.
On closer inspection I see it's not as simple as that.
And I was being US/UK-centric.

I have now come across terms such as 'short scale' and 'long scale' and the word 'milliard' etc, etc.

But it does still seem that it's CLOSE to being a uniform 10^9, no? In that when we hear or read news on science and economics etc we hear of a billion this or a trillion that without any caveats about which VERSION of a billion or a trillion the source is referring to.

Although there's still the matter of 'nonillion'.

Thanks, KerimF

When you say, 'Creation is somehow like creating two opposing equal things from nothing,' what do you mean by 'nothing'?

I remember Lawrence Krauss brought out his book, 'A Universe From Nothing,' but when he promoted the book I got the impression he meant a special

physicist's kind of 'nothing'. He would say things like, 'nothing weighs something', and talk of virtual particles etc.

Thanks, Kerim F.