Can You Help Me Solve This Static Mechanics Problem?

[bostonfenway]

Hi I can't figure out this problem, can you please help me out?
Thank you so much!

http://imageshack.us/scaled/landing/515/19200619.jpg

 

[tiny-tim]

welcome to pf!

hi bostonfenway! welcome to pf!

show us what you've tried, and where you're stuck, and then we'll know how to help!

 

[SteamKing]

First step, figure out the components of P.

 

[bostonfenway]

Thank you for the welcome! :)

This is what I have done so far:

Vertical component = Pcos30 = .866P
Moment arm = 200cos40 = 153.2
Moment= 132.7P (ccw)

Horiz. comp. = Psin30 = .5P
Moment arm = 200 sin40 = 128.6
Moment = -64.3P (cw)

Net moment = 68.4P
Moment arm of P = 68.4

 

[tiny-tim]

hi bostonfenway!

yes that's fine!

(btw, you can check it by seeing it's Pcos20°)

what is worrying you about that? ​

 

[bostonfenway]

its right? So the answer to part a is 68.4?
What about part b? That worries me..

 

[tiny-tim]

its right? So the answer to part a is 68.4?

yes

What about part b? That worries me..​

(b asks for the moment arm)

by definition, the total moment (68.4) equals the total force (200) times the moment arm

 

[bostonfenway]

Got it! Thanks tiny-tim :)