Calculating Torque and Force on Supports A and B

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To calculate the forces on supports A and B for a board of length L with a center of mass x from A, the correct formulas are forceA = mg(L-x)/L and forceB = mg(x)/L. This is derived by taking moments about the supports, ensuring static equilibrium where the sum of downward forces equals the sum of upward forces. The discussion highlights a common mistake in switching the formulas when transferring calculations from paper to a digital format. The importance of double-checking calculations is emphasized to avoid confusion. Accurate torque and force calculations are crucial for structural stability.
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hey. I got a bunch of questions based on this idea, so i want to make sure i got it right before i do everthing.
lets say i got a board sitting between 2 supports A & B. with a length L and a centre of mass x from A. i need to find the force of both endpoints on the supports.
would it be forceA = mg(L-x)L and forceB = mg(x)L ?

thanks
 
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Almost. Taking moments about the two supports and you get.

forceA=mg(L-x)/L and forceB=mg(x)/L

A quick way to check this is that for static equilibrium the downwards forces must equal the upwards forces. In this case, forceA + forceB = mg
 
oh geez. that IS actually what i had done. Honestly. Why won't u believe me?!
I just switched it in my head going from paper to computer.
 

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