Drawing a free body diagram for vectors

  • #1
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.
 

Answers and Replies

  • #2
berkeman
Mentor
58,009
8,070


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?

[3] Show us your math. Is your answer in radians?

[4] Use polar to rectangular conversion formulas:

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

.
 
  • #3


[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?

[3] Show us your math. Is your answer in radians?

[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°?

2)Here is link that I try to made a sketch for question 2.Please check it.
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)
θ=-1.042°(in degree not radian)
But my answer is wrong.
Correct is θ=60°. How?

4)Ok thanks I got link.
 
Last edited by a moderator:
  • #4
tiny-tim
Science Advisor
Homework Helper
25,832
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3)I am using θ=tanˉ¹(y/x)
θ=tanˉ¹(-12/7)
θ=-1.042°(in degree not radian)
But my answer is wrong.
Correct is θ=60°. How?
it's 1.042 radians

i think you pressed the wrong button on your calculator! :redface:
 
  • #5


it's 1.042 radians

i think you pressed the wrong button on your calculator! :redface:
Ok ok thanks. I was wrong. Thanks to help me.
 

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