What is magnitude?

[nehach]

Main Question or Discussion Point

Actually i have just been to class 11th so i m not clear about magnitude so please help me in knowing magnitude and magnitude of displacement...

 

[CompuChip]

Basically, magnitude just means how big it is.
If you have a vector (in, say, three dimensions) $$\vec x = (x_1, x_2, x_3)$$ then the magnitude of that vector is given by (Pythagoras): $$|\vec x| = \sqrt{x_1^2 + x_2^2 + x_3^2}$$.

 

[nehach]

still not very clear how it is related to distance and displacement........then wt is magnitude of displacement.

 

[tiny-tim]

Welcome to PF!

Actually i have just been to class 11th so i m not clear about magnitude so please help me in knowing magnitude and magnitude of displacement...

Hi nehach ! Welcome to PF!

"magnitude" is a long word which means something very simple.

As CompuChip says, it just means how big something is.

For example, if something is displaced along the x-axis by 3, then the magnitude of its displacement is also 3.

But if something is displaced along the x-axis by -3, then the magnitude of its displacement is still 3.

(magnitude is always positive, or zero.)

 

[tonyh]

still not very clear how it is related to distance and displacement........then wt is magnitude of displacement.

Displacement is a vector quantity defined as the change in position - from an initial point i to a final point f. Its magnitude is the length of the straight line between i and f and its direction is from i to f. The actual path taken is irrelevant.
Distance is a scaler quantity defined as the path length, i.e., it does depend on the actual path taken. Distance only equals the magnitude of the displacement for straight line paths.
Hope this hepls

 

[nehach]

if a person start from i and reach to f
distance between i and f is 5 km

i ----------5KM------------f

now kindly tell me what is magnitude and what is displacement
kindly tell me the formula how to calculate both of them

because i am confisued in this

 

[tiny-tim]

Hi nehach!

Displacement: 5 km East.

Magnitude: 5 km.

 

[nehach]

thanks tiny-tim now its clear to me

 

[nehach]

hey could u plz give me ur gmail id so that instead of wasting our time
we can discuss any problem directly
if u think ok
kindly give me ur gmail id

and kindly tell me the formula of calulating both displacement and magnitude

 

[Woozya]

Displacement is a vector quantity. It has direction and magnitude. The absolute quantity of vector is its magnitude.
You can use the formula posted by CompuChip to calculate it
Sorry if I said something wrong

 

[rcgldr]

Simpler still, magnitude is the size or length (always positive or zero) of a vector, independent of the vector direction. "Displacement" in Newtonian physics, is a vector, and has two elements, a signed length (positive, negative, or zero) and a direction.

 

[nehach]

thanks jeff i got it

 

[symbolipoint]

After reading the original post, I know the context is not about stars, but in case anyone is interested:

http://en.wikipedia.org/wiki/Absolute_magnitude

... not meant as distraction nor argument.