home > q&a board > civil engineering > topic: statics 8th edition beer johnston prob 2.36 pg 35 sol...

Q BgQuestion:

Scholar
Karma Points: 200
Respect (100%):
posted by  caveman123456 on 9/9/2008 1:16:10 PM  |  status: Live  

Statics 8th edition Beer Johnston Prob 2.36 pg 35 solution

Course Textbook Chapter Problem
Engineering Mechanics Statics Vector Mech for Eng Beer & Johnston 8th 2 2.36
Question Details:
I have 3 vectors connected at one point. The 90 lb vector is vertical. The second vector and the third vector are tied together. #2 is 70 lb at an angle of theta from the vertical. #3 is pointed downward (with an angle of theta from the -Y axis), 130 lb, in the fourth quadrant. I need to find the magnitude of the resultant vector. ie The two vectors rotate together, the resultant will be along the x-axis (horizontal). I understand the concept - Place the 3 vectors end to end pointing the right direction - the resultant would strech from the origin (horz) to that last vector head. Statics Beer 8th edition prob 2.36
thankyou
Bonus Point Alert! Earn +4 additional karma points for helping this annual member.

AAnswers:

Answer Question
Expert
Karma Points: 1,144
posted by smeaker on 9/9/2008 10:54:38 PM  |  status: Live
Asker's Rating: Helpful   
Response Details:
(a) given that the resultant of the forces is horizontal
Accordingly, ΣFy=0
90lb+70lbsinα=130lbsin(90-α)
90lb+70lbsinα=130lbcosα
by trial and error, we have
α=24degrees

(b) algebraic sum of x-components of the forces is
ΣFx=70lbcos24+130(cos(90-24))
ΣFx=116.82lb
We have
Rx=ΣFx
and Ry=ΣFy
accordingly
R2=Rx2+Ry2
R=√Rx2+Ry2
R=√(ΣFx)2+(0)2
R+ΣFx
R=116.82lb
Hence, magnitude of the resultant is
R=116.82lb

PLEASE RATE!!!!!

Scholar
Karma Points: 200
posted by caveman123456 on 9/10/2008 9:09:54 AM  |  status: Live
Asker's Rating: N/A-Posted by Person Asking Question   
Response Details:
I am new to this website. Your answer made sense to me. I am supprised to see how fast a turn-around I received on the request. While I do not want to "cheat" on my homework sometimes all you need is a clue on how to sovle the problem. Thankyou very much.
Answer Question
Ask New Question

Join Cramster's Community

Cramster.com brings together students, educators and subject enthusiasts in an online study community. With around-the-clock expert help and a community of over 100,000 knowledgeable members, you can find the help you need, whenever you need it. Join for free today » How Cramster is different than tutoring »

Need Help In

Useful Links