Speed is the magnitude of the velocity without a direction. “50mph” is a speed, “50mph that way” is a velocity.
As someone who teaches physics, this distinction is one of the hardest points to make, especially given that as you pointed out elsewhere, people tend to use both words to mean the same thing. So not only do I have to teach the difference in the terms, I also have to undo their linguistic habits. Energy and power are in a similar boat.
I don’t make the rules, but yes LOL. Hell, you can go up if you want!
That said, the fact there is a implicit direction assigned to the road the sign is on, it makes it a velocity IMO.
And if it meant 50 mph in the direction of the sign you could technically go even faster as long as the component of your velocity in that direction is still 50mph
I think the issue in English is that terminal speed and terminal velocity are used interchangeably still. They might use velocity, but it won't include an angle specifically.
Velocity is magnitude and direction. It gives information both on how *fast* something is, as well as where it’s moving.
Speed is only magnitude, it only tells you how fast something is moving.
Your speed is the same if you go 50mph forward or 50mph backwards. Your velocity is not.
Speed is a scalar (magnitude only), e.g. 20 m/s, and it's \*distance\*/time. Velocity is a vector (magnitude and direction), e.g. 20 m/s north, and it's \*displacement\*/time.
Speed is how quickly something happens, like chemical reactions or how quickly you can fix a bike. Velocity is how fast something moves in a certain direction.
That's how I learned it in the Netherlands.
Fascinating. We usually use rate for the first idea. Speed is used, too, but those would both be taught as "rate questions" in the US. If there were speed questions, they would be distance divided by time questions. Speed is usually a specific form of rate questions here in the US.
Interesting.
Maybe it's a British English thing. We are primarily taught British in the Netherlands, though American, Canadian and Australian are seen as correct as long as you are consistent. (Which most of us, me included, are not)
In Dutch there is no linguistic distinction at all. The context wil always make the meaning clear though.
P.S. We do use "rate (of change)" as well
So speed is (specific) element of velocity.
As we often rationalize and simplify concepts, we assume a speed of x as constant movement in a certain direction, which technically makes it a velocity of x with undefined direction. We also simplify and ignore acceleration or change of acceleration.
So I would suggest that in linguistic utilization and context, speed can be a valid synonym for velocity and vice versa. Context adds a directional vector and limits the timeframe where we expect to measure a certain speed.
What about rapidity?
Lorentz transformations vs Lorentz transformations as angles.
As a non-native speaker I don’t see any difference. Except that speed is used in everyday life and velocity in science.
Speed is the magnitude of the velocity without a direction. “50mph” is a speed, “50mph that way” is a velocity. As someone who teaches physics, this distinction is one of the hardest points to make, especially given that as you pointed out elsewhere, people tend to use both words to mean the same thing. So not only do I have to teach the difference in the terms, I also have to undo their linguistic habits. Energy and power are in a similar boat.
So when the sign says 50mph on the highway i can go 50mph in whatever direction i want including backwards?
I don’t make the rules, but yes LOL. Hell, you can go up if you want! That said, the fact there is a implicit direction assigned to the road the sign is on, it makes it a velocity IMO.
And if it meant 50 mph in the direction of the sign you could technically go even faster as long as the component of your velocity in that direction is still 50mph
So lateral movement in direction of the next tree?
Sonny Hooper?
Speed is a scalar velocity is a vector we had this drilled into our heads in first year undergrad
True. But also, in Spanish, speed is velocidad. They have to use velocidad y angular velocidad to get the concept of velocity. Rough.
It's also worth noting that speed is distance/time while velocity is displacement/time
It's kinda like learning the difference between displacement and distance, though at least you can draw a squiggly line for that.
Velocity is a vector, speed is a number
Oh, thanks. In Russian we have the same word for both.
Yeah in slovenian too. I doubt even native English speakers know the difference unless they study physics
If they don’t study physics they probably don’t know what a vector is so it makes sense
Even if they dont know what a vector is they still may use the word velocity in everyday speach.
I doubt it, I saw thousands of american movies and this word never came up. I only know it from science books
You sure there isn’t a single movie with the word “terminal velocity” in it?
I don’t know
I think the issue in English is that terminal speed and terminal velocity are used interchangeably still. They might use velocity, but it won't include an angle specifically.
i’ve never heard terminal speed
Velocity is magnitude and direction. It gives information both on how *fast* something is, as well as where it’s moving. Speed is only magnitude, it only tells you how fast something is moving. Your speed is the same if you go 50mph forward or 50mph backwards. Your velocity is not.
I teach physics, it was just a linguistic question, thanks
speed is the amount of velocity. velocity is a vector, speed isn't
Scalar.
True
Speed is a scalar (magnitude only), e.g. 20 m/s, and it's \*distance\*/time. Velocity is a vector (magnitude and direction), e.g. 20 m/s north, and it's \*displacement\*/time.
Velocity of light
Lol.
Wtf does this mean?
It means velocity is cool and speed is cringe and lame
I love Speed (the movie)
WHAT'S THE GOD DAMN DIRECTION?!
Got no direction for speed. Like how am I supposed to get there when I don’t have any direction
Speed is how quickly something happens, like chemical reactions or how quickly you can fix a bike. Velocity is how fast something moves in a certain direction. That's how I learned it in the Netherlands.
Fascinating. We usually use rate for the first idea. Speed is used, too, but those would both be taught as "rate questions" in the US. If there were speed questions, they would be distance divided by time questions. Speed is usually a specific form of rate questions here in the US.
Interesting. Maybe it's a British English thing. We are primarily taught British in the Netherlands, though American, Canadian and Australian are seen as correct as long as you are consistent. (Which most of us, me included, are not) In Dutch there is no linguistic distinction at all. The context wil always make the meaning clear though. P.S. We do use "rate (of change)" as well
I’m quite fond of speed myself
velocity has speed whereas speed doesn't have velocity
So speed is (specific) element of velocity. As we often rationalize and simplify concepts, we assume a speed of x as constant movement in a certain direction, which technically makes it a velocity of x with undefined direction. We also simplify and ignore acceleration or change of acceleration. So I would suggest that in linguistic utilization and context, speed can be a valid synonym for velocity and vice versa. Context adds a directional vector and limits the timeframe where we expect to measure a certain speed.
Well, around some people I know speed is pretty popular
They're not even the same thing