Poll: Negative Miles per Hour

[bryanfuel]

I was wondering if it is possible to go negative miles per hour. Is it counted as negative mph or does it count as going positive mph in the opposite direction. Also if it was possible to go negative mph would you go back in time? Please help settle this argument with me and my friend. I'm not going to put my opinion because I don't want to influence the poll.

 

[riskroWe]

Negative velocity indicates negative displacement, and thus direction.
You're moving backwards.
EDIT: In space, not in time.

 

[benylor]

This is a question of semantics. As such, I'm afraid to say that I can't discriminate which of the two arguments is more foolish - they are both equally so.

Okay, it depends on if you're talking of speed or velocity. If you're thinking about speed, then it's positive always. You can't get a negative speed.
If you're thinking about Velocity, and your example implies 1-dimensional velocity (which means I don't have to write a few extra paragraphs, I think), then one direction is defined as positive. That means that movement in the non-positive direction would, indeed, be negative velocity.

My answer, is to stop arguing and recognise that you're arguing over a vaguity in wording. "Negative miles per hour" is valid, if and only if you are working with vectors and thus if and only if it's velocity you're on about. Otherwise, if working with the scalar speed, it is nonsense.

Does this answer your question?

 

[Altorin]

Negative velocity indicates negative displacement, and thus direction.
You're moving backwards.
EDIT: In space, not in time.

basically this.

You can go negative miles per hour in a velocity (as in, speed in a given direction), but if you're just measuring speed, then you are going at whatever speed you're going negative.

 

[bryanfuel]

This is a question of semantics. As such, I'm afraid to say that I can't discriminate which of the two arguments is more foolish - they are both equally so.

Okay, it depends on if you're talking of speed or velocity. If you're thinking about speed, then it's positive always. You can't get a negative speed.
If you're thinking about Velocity, and your example implies 1-dimensional velocity (which means I don't have to write a few extra paragraphs, I think), then one direction is defined as positive. That means that movement in the non-positive direction would, indeed, be negative velocity.

My answer, is to stop arguing and recognise that you're arguing over a vaguity in wording. "Negative miles per hour" is valid, if and only if you are working with vectors and thus if and only if it's velocity you're on about. Otherwise, if working with the scalar speed, it is nonsense.

Does this answer your question?

ya i guess but its pretty complicated

 

[rees263]

When you are dealing with vectors it is possible to have negative speed, but for all intents and purposes it means going in the opposite direction. Think about it like this - you are either moving or not moving. If you are moving then you have a quantifiable (positive) speed.

The answer I'm sure would be different when applied to quantum mechanics but I only have a very basic understanding of it so I don't know what that answer would be.

The last thing to bear in mind is that the axioms on which mathematics is based are pretty arbitrary - it's entirely possible to invent a new set of axioms so you could get a negative speed, and you could use it to mean pretty much anything. That's really theoretical though, and bordering on the philosophical.

In summary, in real world maths, no, you can't have negative speed.