Draw a Free Body Diagram to find reactions.

InfoJunkie4Life · Feb 17, 2010, 01:59 PM

The weight is 60% towards B and 40% towards A so 60% of the weight will be on B (4.8kN) while 40% will be on A (3.2kN). The rollers really don't affect anything unless you're including the flex of the plank in the mix, or height of points, or pressure on the ground. Both will be pointing up, and unless something moves, there should be equilibrium.

leeroynew · Feb 18, 2010, 12:03 AM

This is what I got, I just didn't think the answer could be as simple as this lol.

Thanks for the help.

Unknown008 · Feb 18, 2010, 07:22 AM

I you want to use the principles of moments, you'll have to do it this way:

As the system is in equilibrium, all clockwise moment are equal to anticlockwise moments.

Taking A as pivot, you have two forces on the system, the 8kN mass and the B support.

Moment due to mass = Fd = (8 kN)(3 m) = 24 kNm
Moment due to support B = Fd = (B kN)(5 m) = 5B kNm

Since they are equal,
24 kNm = 5B kNm
24 = 5B
B = 24/5 = 4.8 kN

Then, since the mass is spread on the two supports, A support (8 kN - 4.8 kN) = 3.2 kN.

Draw a Free Body Diagram to find reactions.

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