# The difference between Speed and Velocity

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Although this is a very simple question, I yet can't understand it.

What is the difference between speed and velocity?

I know that velocity has a direction, but what differnce does that make? Till now, I learn it off by heart, can anyone explain why does the velocity change as the direction changes?

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SPEED ==> The rate or a measure of the rate of motion, especially: Distance traveled divided by the time of travel.

VELOCITY ==> A vector quantity whose magnitude is a body's speed and whose direction is the body's direction of motion.

(APP & SES 2003 & 2002)

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for futher infomation.

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I understand it now

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• 4 months later...

hmm,velocity and speed are often similar-they have the same numbers

but AVERAGE velocity and AVERAGE speed ain't-they don't have the same numbers in most cases.

i didn't know the true difference between velocity and speed before that.

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For 100m swimming, after the swimmer had finished their race, they have 0 velocity but a speed with greater than 0 m/s.

Why?

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For 100m swimming, after the swimmer had finished their race, they have 0 velocity but a speed with greater than 0 m/s.

aommaster, if you understood what they said on that page (link) then you understood all of it.

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Velocity=Displacement/time

Displacement=0

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aommaster' date=' if you understood what they said on that page (link) then you understood all of it.[/quote']

ok!

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Velocity=Displacement/time

Displacement=0

I suggest you try to understand that link.

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an n dimensional vector needs n mubers to speficy it. For example a 3-dimensional vector can be expressed in terms of three numbers v_1, v_2 and v_3

$\vec{v} = v_1\hat{i} + v_2\hat{j} + v_3\hat{k}$

Where the i, j and k are some (usually orthogonal, but not necessarily) unit vectors

or simply by a matrix:

$\vec{v} = \left(\begin{array}{c}v_1\\v_2\\v_3\end{array} \right)$

So the difference between speed and velcotiy is importnat, because velocity (in three dimensions requires 3 numbers to specify it, whereas speed only rrequires one number.

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Velocity=Displacement/time

Displacement=0

The velocity is the derivative with respect to time of displacement. Wht you mentioned is average velocity not instantaneous velocity.

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Another nice way to appreciate difference between speed and velocity, is to analyse a particle moving in a circle with a constant speed v. Even though speed remains the same, the velocity constantly varies due to direction change.

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The velocity is the derivative with respect to time of displacement. Wht you mentioned is average velocity not instantaneous velocity.

I think what he was trying to say is that velocity is given by:

$\lim_{\Delta t \rightarrow 0} \frac{\Delta r}{\Delta t}$

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Or more simply [MATH] \vec{v}=\frac{d\vec{r}}{dt}[/MATH]

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I think what he was trying to say is that velocity is given by:

Are you saying me?

I was trying to use the case of swimming to explain some "tricky"questions to him.

lol

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No, I think he means pulkit.

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I am wrong again........;p

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• 1 month later...

You guys are all a bunch of science nerds. i mean my god who actually goes onto these sites to ask about homework or science stuff! i mean seriously! you guys have no life, you need to get out more

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And you don't see the irony of taking the time to seek out such a forum, signing up, and then posting that comment?

My god your life must be desolate.

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You guys are all a bunch of science nerds. i mean my god who actually goes onto these sites to ask about homework or science stuff! i mean seriously! you guys have no life, you need to get out more
Gobbles, you are so right. Let's see this year I've watched the sun set over the beach in Perth, Australia while drinking a ice cool beer; I've walked on a glacier in Norway in the company of friends; I've had the worst Indian meal ever in Amsterdam and the best in Aberdeen; I've travelled down the Mekong on hydrofoil, I've visited the Botanic Gardens in Bogor, on the island of Java; I've delivered lectures to small groups of students, totalling over three hundred on four continents; I've contributed to sales efforts for my company that have generated in excess of $20,000,000; and throughout it all I've continued to play the piano very badly. Its just as well I still have November and December left to actually do something in. ##### Link to comment ##### Share on other sites Gobbles, you are so right. Let's see this year I've watched the sun set over the beach in Perth, Australia while drinking a ice cool beer; I've walked on a glacier in Norway in the company of friends; I've had the worst Indian meal ever in Amsterdam and the best in Aberdeen; I've travelled down the Mekong on hydrofoil, I've visited the Botanic Gardens in Bogor, on the island of Java; I've delivered lectures to small groups of students, totalling over three hundred on four continents; I've contributed to sales efforts for my company that have generated in excess of$20,000,000; and throughout it all I've continued to play the piano very badly. Its just as well I still have November and December left to actually do [/b']something in.

Ophiolite, I think you are on the wrong forum

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I hope gobbles dies soon........

(just kidding )

It seems odd that YOU signed up for it though.

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Gobbles, you are so right. Let's see this year I've watched the sun set over the beach in Perth, Australia while drinking a ice cool beer; I've walked on a glacier in Norway in the company of friends; I've had the worst Indian meal ever in Amsterdam and the best in Aberdeen; I've travelled down the Mekong on hydrofoil, I've visited the Botanic Gardens in Bogor, on the island of Java; I've delivered lectures to small groups of students, totalling over three hundred on four continents; I've contributed to sales efforts for my company that have generated in excess of \$20,000,000; and throughout it all I've continued to play the piano very badly. Its just as well I still have November and December left to actually do [/b']something in.

This year I went to ottawa on a class trip. It was fun.

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