Physics/Mechanics Equilibrium Force Question

AI Thread Summary
The discussion revolves around calculating the reaction forces at points A and B for a uniform bar supported by a pin and roller, with a mass of 100 kg/m and an angle of 60 degrees. The user attempts to solve the problem using equilibrium equations, calculating the vertical reaction force at B (BY) as 6.389 kN and the vertical reaction force at A (AY) as 6.018 kN. Additionally, the horizontal reaction force at A (AX) is determined to be 1.2 kN. Feedback indicates that the free body diagram (FBD) is incorrect, particularly regarding the left-hand load, and suggests verifying calculations by taking moments about a different point. The discussion emphasizes the importance of accurate FBDs and moment calculations in solving equilibrium problems.
bob29
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Homework Statement


Find the reaction forces of A and B.
Uniform bar with a mass of 100kg/m supported by a pin and a roller.
\Theta = 60
g=9.81m/s2
[URL]http://img340.imageshack.us/i/mechanicsproblem.jpg/[/URL]
[URL]http://img340.imageshack.us/i/mechanicsproblem.jpg/

Homework Equations


Moment/torque = Force*Displacement
Sum of MA=0 (moment about point A)
Sum of FY=0
Sum of FX=0

The Attempt at a Solution


Taking M about point A. (Counter-clockwise as +ve)
9BY - (1500N*7m) - (2400N*sin(60) * 3.5m) - [100kg/m*9m*9.81m/s2*(1/2*9m)]=0
9BY = 57,505N
BY = 6.389kN
B = 6.389kN​

Sum of FY=0
AY + BY - 2.4kN*sin(60) - 1.5kN - (W=8.829kN) = 0
AY = 6.018kN​

Sum of FX=0
AX - 2.4kN*cos(60) = 0
AX = 1.2kN​
Would like to verify whether my attempt at the question is correct, as well as my free body diagram.
 
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A diagram for the question would help.
 
Sorry, Iv'e just found the link to the figure. Your fbd is not correct at the left hand load. Something missing there. You can check your own work by taking moments about any point other than A.
 

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