# Drawing a free body diagram for vectors

I have some question related to vectors.

1)How will you find a vector(A) if you given another vector(B) in +x-direction to give a resultant(R) at θ(any degree)?

2)A child is holding a wagon from rolling straight back down a driveway that is inclined at 20° to horizontal. If the wagon weighs 150N, with what force must the child pull on the handle if the handle is at 30° above the incline?(This question is asked by a friend. I tried but I am not able to get answer. I told him that I will ask an expert then tell you.)

3)Find the magnitude and angle of R if R=7.0i-12j
I did not get to angle, my θ=-1.042. Is my answer wrong?

Last question
4)If you give a vector in form of its magnitude and ask to write it in the form of unit vectors(i,j,k) then how will do it?

Any help is appreciable. Thanks in advance.

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berkeman
Mentor

I have some question related to vectors.

1)How will you find a vector(A) if you given another vector(B) in +x-direction to give a resultant(R) at θ(any degree)?

2)A child is holding a wagon from rolling straight back down a driveway that is inclined at 20° to horizontal. If the wagon weighs 150N, with what force must the child pull on the handle if the handle is at 30° above the incline?(This question is asked by a friend. I tried but I am not able to get answer. I told him that I will ask an expert then tell you.)

3)Find the magnitude and angle of R if R=7.0i-12j
I did not get to angle, my θ=-1.042. Is my answer wrong?

Last question
4)If you give a vector in form of its magnitude and ask to write it in the form of unit vectors(i,j,k) then how will do it?

Any help is appreciable. Thanks in advance.
[1] Use trigonometry. Can you draw us a sketch?

[2] Start by drawing a free body diagram (FBD). Can you draw that for us, and label the forces on it?

[4] Use polar to rectangular conversion formulas:

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

.

[1] Use trigonometry. Can you draw us a sketch?

[2] Start by drawing a free body diagram (FBD). Can you draw that for us, and label the forces on it?

[4] Use polar to rectangular conversion formulas:

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

.
1)Here is an example question for what I am asking you.
What displacement must be added to a 50cm displacement in the +x-direction to give a resultant displacement of 85cm at 25°?

http://s1227.photobucket.com/albums/ee430/Shayaan_Mustafa/Album%201/?action=view&current=untitled.jpg [Broken]

3)I am using θ=tanˉ¹(y/x)
θ=tanˉ¹(-12/7)
Correct is θ=60°. How?

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tiny-tim
Homework Helper
3)I am using θ=tanˉ¹(y/x)
θ=tanˉ¹(-12/7)
Correct is θ=60°. How?

i think you pressed the wrong button on your calculator!