Q BgQuestion:

Rookie
Karma Points: 11
Respect (38%):
posted by  LizDarcy on 10/11/2008 12:53:27 PM  |  status: Live  

Equilibrium (Force & Torque)...Immediate Help Plz

Course Textbook Chapter Problem
General Physics N/A N/A N/A
Question Details:
A house painter is standing on a uniform, horizontal platform that is held in equilibrium by two cables attached to supports on the roof. The painter has a mass of 74 kg and the mass of the platform is 19.6 kg. The distance from the left end of the platform to where the painter is standing is d = 1.8 m and the total length of the platform is 5.4 m.

(a) How large is the force exerted by the left-hand cable on the platform?
N

(b) How large is the force exerted by the right-hand cable?
I know this problem requires three equations: 2 Force component equations and one torque equation but i don't know how to go about it
 

AAnswers:

Answer Question
(Cramster SME)
posted by Justin_08 on 10/11/2008 3:14:28 PM  |  status: Live
Asker's Rating: Lifesaver   
LizDarcy's comment:
"Thanks soooooooooooooooooo much :-)"
Response Details:
 
 
             Given that the mass of the painter is  m = 74 Kg
            The mass of the platform is  M = 19.6 kg
             The length of the platform is L = 5.4 m
          -----------------------------------------------------------------
 
               The situation is as shown in the figure 
 
                          
 
   apply momet of force about point A then we get  ( take torque is positive along counter clockwise)
 
                   Fa*(0) - Mg*(AB) - m*g(AC) + Fb*AD = 0            
                                  Mg*(L/2) + mg(d) = Fb*L 
                                  
              then we get the force  Fb = ---------- N
 
      Since the system is in equalibrium then  we get
 
                             ΣFy = 0
                       Fa - Mg - m*g + Fb = 0
                       Fa =  W + Wp - Fb                              
                            = ------------- N  
  where  Fa and Fb are the tentions in the two strings 
 
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 »