Speed versus velocity?

ReadyAndWilling · April 23 2010, 03:23 AM

hey guys, can anyone explain to me the difference between speed and velocity?

thanks

sojourner · April 23 2010, 06:05 AM

http://dictionary.reference.com/browse/speed

http://dictionary.reference.com/browse/velocity

Um, none?

PurpleBuddha · April 23 2010, 06:13 AM

ReadyAndWilling wrote:

hey guys, can anyone explain to me the difference between speed and velocity?

thanks

Do you mean acceleration vs velocity?

sojourner · April 23 2010, 06:19 AM

^ Yea, that's easy. Acceleration is how long it takes something to get up to speed.

Example:

You know a car can do 60mph. 60mph is the speed.

How long does it take the car to go from 0mph to 60mph? That would be it's rate of acceleration.

PurpleBuddha · April 23 2010, 06:30 AM

^ That.

Or put even more simply, acceleration is the rate of change in velocity.

Pavonis · April 23 2010, 02:20 PM

Speed is a scalar.

Velocity is a vector.

That's a distinct and fundamental difference between the two terms.

It's the difference between "Drive 50 mph to get to my house" and "Drive 50 mph north to get to my house".

Jadzia · April 23 2010, 02:34 PM

It's similar to the distinction between distance and position.

Lindley · April 23 2010, 03:44 PM

Pavonis wrote:

Speed is a scalar.

Velocity is a vector.

That's a distinct and fundamental difference between the two terms.

It's the difference between "Drive 50 mph to get to my house" and "Drive 50 mph north to get to my house".

That's it exactly.

A velocity in 3D space might look like <5, 6, 7> in the x,y,z directions. But the assocated speed would be sqrt(5*5+6*6+7*7) = 10.5.

Speed and velocity reduce to the same thing in a 1-dimensional space.

Asbo Zaprudder · April 23 2010, 04:03 PM

Lindley wrote:

Speed and velocity reduce to the same thing in a 1-dimensional space.

[nitpick] Not quite, an object could have a speed of 5 m/s in either the +ve or -ve direction, which would be equivalent to velocities of +5 m/s or -5 m/s respectively. [/nitpick]

Lindley · April 23 2010, 04:07 PM

Okay, granted.

ReadyAndWilling · April 24 2010, 04:38 PM

Pavonis wrote:

Speed is a scalar.

Velocity is a vector.

That's a distinct and fundamental difference between the two terms.

It's the difference between "Drive 50 mph to get to my house" and "Drive 50 mph north to get to my house".

hey man, thanks for the reply. can you explain that example a bit more?

The Badger · April 24 2010, 04:57 PM

Speed is how fast something travels.

Velocity is how fast something travels in a particular direction.

sojourner · April 24 2010, 06:17 PM

^Sounds the same to me. Unless you view velocity as a subset of speed?

FordSVT · April 24 2010, 06:18 PM

I'll say it again in another way just for fun!

Speed = rate of movement over time. 50 meters per second, a scalar quantity.
Velocity = rate of movement over time + a direction. 50 meters per second @ 45 degrees, a vector quantity.

Ooooo! Ooooo! Rule of thumb! Rule of thumb! Lets add some!

DonIago · April 24 2010, 06:36 PM

Velocity specifies direction, speed does not.

April 23 2010, 03:23 AM	#1
ReadyAndWilling Fleet Captain	Speed versus velocity? hey guys, can anyone explain to me the difference between speed and velocity? thanks

April 23 2010, 06:05 AM	#2
sojourner Vice Admiral Location: I'm at WKRP	Re: Speed versus velocity? http://dictionary.reference.com/browse/speed http://dictionary.reference.com/browse/velocity Um, none? __________________ Baby, you and me were never meant to be, just maybe think of me once in a while...

April 23 2010, 06:19 AM	#4
sojourner Vice Admiral Location: I'm at WKRP	Re: Speed versus velocity? ^ Yea, that's easy. Acceleration is how long it takes something to get up to speed. Example: You know a car can do 60mph. 60mph is the speed. How long does it take the car to go from 0mph to 60mph? That would be it's rate of acceleration. __________________ Baby, you and me were never meant to be, just maybe think of me once in a while...

April 23 2010, 06:30 AM	#5
PurpleBuddha Rear Admiral	Re: Speed versus velocity? ^ That. Or put even more simply, acceleration is the rate of change in velocity. __________________ We establish no religion in this country, we command no worship, we mandate no belief, nor will we ever. Church and state are, and must remain, separate. -Ronald Reagan

April 23 2010, 02:20 PM	#6
Pavonis Commodore Location: South Dakota	Re: Speed versus velocity? Speed is a scalar. Velocity is a vector. That's a distinct and fundamental difference between the two terms. It's the difference between "Drive 50 mph to get to my house" and "Drive 50 mph north to get to my house".

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April 23 2010, 02:34 PM	#7
Jadzia on holiday Location: England	Re: Speed versus velocity? It's similar to the distinction between distance and position. __________________ .

April 23 2010, 04:07 PM	#10
Lindley Moderator with a Soul Location: Fairfax, VA	Re: Speed versus velocity? Okay, granted. __________________ Lead Organizer for EVN: Firefly. "So apparently the really smart zombies have automatic weapons!" -Torg, Sluggy Freelance

April 24 2010, 04:57 PM	#12
The Badger Fleet Captain Location: Im in ur Tardis, violating ur canon.	Re: Speed versus velocity? Speed is how fast something travels. Velocity is how fast something travels in a particular direction.

April 24 2010, 06:17 PM	#13
sojourner Vice Admiral Location: I'm at WKRP	Re: Speed versus velocity? ^Sounds the same to me. Unless you view velocity as a subset of speed? __________________ Baby, you and me were never meant to be, just maybe think of me once in a while...

April 24 2010, 06:18 PM	#14
FordSVT Vice Admiral Location: Atlantic Canada	Re: Speed versus velocity? I'll say it again in another way just for fun! Speed = rate of movement over time. 50 meters per second, a scalar quantity. Velocity = rate of movement over time + a direction. 50 meters per second @ 45 degrees, a vector quantity. Ooooo! Ooooo! Rule of thumb! Rule of thumb! Lets add some! __________________ -FordSVT-

April 24 2010, 06:36 PM	#15
DonIago Rear Admiral Location: Burlington, VT, USA	Re: Speed versus velocity? Velocity specifies direction, speed does not. __________________ --DonIago It was the best of Trek, it was the worst of Trek... "If I lean over, I leave myself open to wedgies, wet willies, or even the dreaded Rear Admiral!"