graphical method to find magnitude and direction

tiny-tim

Quote by xupe33jrm

The force vector FA has a magnitude of 90.0 newtons and points
due east. The force vector FB has a magnitude of 135 newtons and
points 75° north of east. Use the graphical method and find the
magnitude and direction of (a) FA - FB (give the direction with respect
to due east) and (b) FB + FA (give the direction with respect
to due west).

Quote by isyndhrea

based to my friend the graph is like this..?

for F_A + F_B, yes

isyndhrea

what graph is correct?

is this problem use pythagorean theorem or component method?

tiny-tim

you can always use either the cosine formula or the component method

(pythagoras only works for right-angled triangles … for general triangles you need the cosine formula)

isyndhrea

actually this is in my book .. FB-FA due to west

and first i used component method which is

x=90 y=0
x= 35 y=130

sum= x=125 y= 130

then i used pythgorean theorem

isyndhrea

. cosine formula?.. our professor did not teach about that..

tiny-tim

Quote by isyndhrea

actually this is in my book .. FB-FA due to west

and first i used component method which is

x=90 y=0
x= 35 y=130

sum= x=125 y= 130

then i used pythgorean theorem

(that's FB plus FA)

ah, i see what you mean …

yes, when you have the x and y components, you can then use the pythgorean theorem to give you the magnitude

(your answer should be "a magnitude of … newtons at an angle of … north of west")

isyndhrea

yes, when you have the x and y components, you can then use the pythgorean theorem to give you the magnitude

(your answer should be "a magnitude of … newtons at an angle of … north of west")[/QUOTE]

-is only one answer for this problem?..

isyndhrea

but the result is not 142 ang 67 degree.

isyndhrea

can you give me a specific formula?

tiny-tim

that's 67° north of east, the question asks for the angle with respect to west

tiny-tim

Quote by isyndhrea

actually this is in my book .. FB-FA due to west

and first i used component method which is

x=90 y=0
x= 35 y=130

sum= x=125 y= 130

then i used pythgorean theorem

also, you've added the components instead of subtracting them

isyndhrea

so if i subtract the angle will be in north of west

alex.hs

Hi guys.....
I am new to his website and i dunno if i am using the correct place to ask my question

Well the question is:
When a vector is given say A: a i^+b j^+ck^ then how to find the angle between the vector and x-axis: y- axis; z-axis
Thanq for ur time ......

Infinitum

Quote by alex.hs

Hi guys.....
I am new to his website and i dunno if i am using the correct place to ask my question

Well the question is:
When a vector is given say A: a i^+b j^+ck^ then how to find the angle between the vector and x-axis: y- axis; z-axis
Thanq for ur time ......

Hi alex.hs! Start a new thread about your question. Make sure you include an attempt along with it!

For starters, to find angle from x axis, think about taking an unit vector along x-axis, and use the concept of dot-product.

Similar Threads for: graphical method to find magnitude and direction
Thread	Forum	Replies
find the direction and magnitude of the resultant forces	Precalculus Mathematics Homework	3
How do you find the direction of a vector given its magnitude and angle?	Introductory Physics Homework	2
Find the magnitude and direction of force in a dipole	Advanced Physics Homework	1
Find position, magnitude, and direction...	Introductory Physics Homework	1
How do you find the direction and magnitude from a nucleus?	Introductory Physics Homework	1

isyndhrea	what graph is correct? is this problem use pythagorean theorem or component method?

tiny-tim Blog Entries: 27 Recognitions: Gold Member Homework Help Science Advisor	you can always use either the cosine formula or the component method (pythagoras only works for right-angled triangles … for general triangles you need the cosine formula)

isyndhrea	can you give me a specific formula? Attached Thumbnails

alex.hs	Hi guys..... I am new to his website and i dunno if i am using the correct place to ask my question Well the question is: When a vector is given say A: a i^+b j^+ck^ then how to find the angle between the vector and x-axis: y- axis; z-axis Thanq for ur time ......