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Finding the Resultant Force, help needed.

  • Thread starter Dellis
  • Start date
  • #1
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0
Hi, I need some guidance regarding this exercise, I attached a visual representation of the exercise

Homework Statement



Find the Resultant Force for the following system of forces shown


FORCES SHOWN on a Vector:


F1= 5 kips on the X quadrant in a 60 degree angle

F2= 5 kips straight down on the Y axis

F3= 8 kips on the X quadrant in a 30 degree angle



Homework Equations



These right?

Rx= [tex]\Sigma[/tex]Fx= F1 + F2 + F3
Ry=[tex]\Sigma[/tex]Fy= F1 + F2+ F3


(theta)Qx= Tan- Ry/Rx


The Attempt at a Solution




I want to know if I am going in the right direction, if not please guide me, this is what I tried.


Rx= [tex]\Sigma[/tex]Fx= F1 + F2 + F3

=+5(sin 60 )- 5 + 8(cos 30 )

= -6.16 kips


Ry=[tex]\Sigma[/tex]Fy= F1 + F2+ F3

= -5( sin 60)-5 + 8 (cos 30)

= -8.571 kips
 

Attachments

Last edited:

Answers and Replies

  • #2
rl.bhat
Homework Helper
4,433
7
In ΣFx, there is no F2 and F1x = F1*cosθ.
In ΣFy, F1x is positive, and F3x = F3sinθ and it is negative.
 
  • #3
90
0
In ΣFx, there is no F2 and F1x = F1*cosθ.
In ΣFy, F1x is positive, and F3x = F3sinθ and it is negative.
So like this right?


Rx= [tex]\Sigma[/tex]Fx= F1 + F3

=+5(cos 60 ) x 8(cos 30 )

= answer here


Ry=[tex]\Sigma[/tex]Fy= F1 + F2+ F3

= 5( sin 60)-5 + 8 (sin 30)

= answer here
 
  • #4
rl.bhat
Homework Helper
4,433
7
Note down whether the components are on the +ve or -ve axis.
 
  • #5
90
0
This is the next steps right?


R= [tex]\sqrt[]{}[/tex] Rx+ Ry

= answer here


then...


(theta)Qx= TAN-Ry/Rx

= answer here
 
Last edited:
  • #6
90
0
Note down whether the components are on the +ve or -ve axis.
What do you mean?, my english understanding isn't that great can you say that in another way.

I just want assurance that I am on the right path, thanks for the help btw I appreciate it.
 
Last edited:
  • #7
rl.bhat
Homework Helper
4,433
7
So like this right?


Rx= [tex]\Sigma[/tex]Fx= F1 + F3

=+5(cos 60 ) x 8(cos 30 )

= answer here


Ry=[tex]\Sigma[/tex]Fy= F1 + F2+ F3

= 5( sin 60)-5 + 8 (sin 30)

= answer here
=+5(cos 60 ) x 8(cos 30 ) This step should be

=-5(cos 60 ) + 8(cos 30 )
5( sin 60)-5 + 8 (sin 30) This step should be
5( sin 60)-5 - 8 (sin 30)
 
  • #8
90
0
=+5(cos 60 ) x 8(cos 30 ) This step should be

=-5(cos 60 ) + 8(cos 30 )
5( sin 60)-5 + 8 (sin 30) This step should be
5( sin 60)-5 - 8 (sin 30)
I had it like that then got confused by your advise that said " *cos " and I took that as you saying multiply then I added an X, sorry lol.

Thanks for clearing that up, so the next steps I showed you in post#5 above is the right path correct?, that would pretty much wrap this exercise up, I will proceed once you tell me.
 
Last edited:
  • #9
rl.bhat
Homework Helper
4,433
7
Carry on with post5#
 
  • #10
90
0
Alright thanks, I appreciate the help and guidance :)
 

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