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#1 2006-03-03 10:17:25
- mikau
- Member
- Registered: 2005-08-22
- Posts: 1,504
velocity isn't speed?
Today my book asked for the average velocity of a function AND the average speed of a function. Huh? I thought velocity and speed were the same thing and would have bet my life on it!
Somebody please explain this madness.
A logarithm is just a misspelled algorithm.
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#2 2006-03-03 10:23:19
- Patrick
- Real Member
- Registered: 2006-02-24
- Posts: 1,005
Re: velocity isn't speed?
http://en.wikipedia.org/wiki/Velocity
and
http://en.wikipedia.org/wiki/speed
Havn't really had any of this yet, but you might find the answers there..
As far as I understand, velocity is a vector and speed is not..
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#3 2006-03-03 10:30:26
- mikau
- Member
- Registered: 2005-08-22
- Posts: 1,504
Re: velocity isn't speed?
OOoooh... I think I got it. speed = |velocity|
A logarithm is just a misspelled algorithm.
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#4 2006-03-03 11:27:42
- mathsyperson
- Moderator
- Registered: 2005-06-22
- Posts: 4,900
Re: velocity isn't speed?
Yep, that's precisely it. With velocity, direction is important, but with speed it is not.
If you ran around in circles, your speed would be constant, but your velocity would be constantly changing. Your average velocity would be zero!
Why did the vector cross the road?
It wanted to be normal.
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#5 2006-03-03 12:00:32
- Ricky
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- Registered: 2005-12-04
- Posts: 3,791
Re: velocity isn't speed?
If you ran around in circles, your speed would be constant, but your velocity would be constantly changing. Your average velocity would be zero!
And so would your IQ.
Take that, track team.
"In the real world, this would be a problem. But in mathematics, we can just define a place where this problem doesn't exist. So we'll go ahead and do that now..."
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#6 2006-03-03 12:38:53
- mikau
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- Registered: 2005-08-22
- Posts: 1,504
Re: velocity isn't speed?
here here, ricky!
A logarithm is just a misspelled algorithm.
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#7 2016-12-01 15:20:49
- Monox D. I-Fly
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- From: Indonesia
- Registered: 2015-12-02
- Posts: 2,000
Re: velocity isn't speed?
OOoooh... I think I got it. speed = |velocity|
Wait... Does it imply that speed can be negative? O.o
Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.
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#9 2016-12-02 16:01:51
- Monox D. I-Fly
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- From: Indonesia
- Registered: 2015-12-02
- Posts: 2,000
Re: velocity isn't speed?
How? Never encountered any.
Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.
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#10 2016-12-02 21:01:35
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: velocity isn't speed?
There is a formula for motion under a constant acceleration:
v = u + at
v is the final velocity; u the initial velocity; a the acceleration and t the time taken.
If an object is thrown upwards the student has to decide if 'up' is the positive direction for velocity, in which case the acceleration is negative. Both are vector quantities. Or you can take acceleration as positive, which makes v negative. It is not usual to consider time as negative, but it is a scalar anyway. I have encountered problems where the solution was a negative t, meaning an event happened before the start time.
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob 
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