Vectors and Scalar Quantities (1 Viewer)

[747captain]

Just began some work in class today about the following:

• vector
• scalar
• displacement
• scalars are the magnitude of the corresponding vectors
• displacement/time graphs

My teacher ain't very good, and I kinda struggled to understand it all. I read my textbook twice (Physics 1) but still don't fully understand. Anyone know a good website or have some notes or something which could help.

Thanks heaps.

Cheers

 

[PrettyVacant]

Vectors have magnitude and direction, whereas scalars only have magnitude.


Eg. Velocity has to be Xms^-1 (+ A direction) - That's vector.
Speed only has to be Xms^-1 - No direction, that is scalar.

Displacement is a vector, distance is a scalar.
Displacement requires a direction as well. I mean, you can say "I live 100kms from here" - that's the distance, but if someone asked for the displacement of you from your house, you'd have to say, "100kms WEST/East/b160 etc."
If you walk in a circle, and return to the starting point, your total displacement is zero. But your distance travelled is the circumference of the circle you just walked.

Man, I've written so many notes on this ^^

 

[747captain]

Thanks PrettyVacant,

But what does it mean "scalars are the magnitude of the corresponding vectors"?

 

[dr baby beanie]

Also just so more info, changing velocity means acceleration ie you're going around in a circle, your speed might be/is constant, but since you're direction is changing, you're velocity is also changing .: acceleration.

 

[PrettyVacant]

You mean vector diagrams?

Uh, I"m sure we've done it in class 'cause we've finished "moving about" but I think the wording is somewhat offputting.

 

[dr baby beanie]

Thanks PrettyVacant,

But what does it mean "scalars are the magnitude of the corresponding vectors"?

magnitude = size.

scalars represent the size of a vector (they lack direction, so basically a scalar quantity is just a "size", a vector incorporates both size and direction - if you get me)

edit: if I'm wrong, I'm very sorry (but someone will correctly)

 

[Forbidden.]

Thanks PrettyVacant,

But what does it mean "scalars are the magnitude of the corresponding vectors"?

distance = | displacement |

lol thats how i remember ... absolute values ftw ...

Scalar quantities only have a size.
Vector quantities have a size AND direction relative to the origin.

 

[ianc]

Have a look at this site
http://www.physclips.unsw.edu.au/jw/vectors.htm

You can ignore the final sections relating to "dot product" and "cross product" - but most of that page should be useful to you. Also, you may or may not need to know about unit vectors - but they are not at all hard, just a different method of notation

The physics people at UNSW have a whole resources site which could be quite useful for you both now and later on during your hsc year, so i recommend bookmarking it: http://www.phys.unsw.edu.au/hsc/index.html. Last year I found many things on that site both interesting and useful.

Also, the Physics HSC forum (https://www.phys.unsw.edu.au/forums/viewforum.php?f=13) may provide an additional avenue for you to get your physics questions answered other than bos.

Hope this is of some help to you!

 

[watatank]

distance = | displacement |

lol thats how i remember ... absolute values ftw ...

Scalar quantities only have a size.
Vector quantities have a size AND direction relative to the origin.

Negatory.

Corrections:

dont confuse the poor man by saying distance =/= | displacement |

displacement is the straight line distance (with direction) between the start and end points. distance is well, the distance. consider a 400m race around an athletics track. distance = 400, displacement = 0 (start, end in same place)

scalar quantities have only a magnitude (like speed, distance, mass, etc)
vector quantities have a magnitude and direction (velocity, displacement, acceleration, force)

Vector quantities have a size AND direction relative to something else, usually taken to be the earth but can easily be another object. it doesnt always need to be the "origin", watever thats supposed to mean.

 

[Forbidden.]

Negatory.

Corrections:

dont confuse the poor man by saying distance =/= | displacement |

displacement is the straight line distance (with direction) between the start and end points. distance is well, the distance. consider a 400m race around an athletics track. distance = 400, displacement = 0 (start, end in same place)

scalar quantities have only a magnitude (like speed, distance, mass, etc)
vector quantities have a magnitude and direction (velocity, displacement, acceleration, force)

Vector quantities have a size AND direction relative to something else, usually taken to be the earth but can easily be another object. it doesnt always need to be the "origin", watever thats supposed to mean.

It was all taken from the HSC Mathematics Excel Book, you could complain to the author herself if you disregard the distance = | displacement |, because it was in one of the study guides in the Applications of Calculus to the Physical Word section.

 

[747captain]

Thanks so much to everyone.

I finally understand!

Once again, thanks everyone.

Cheers