Manually calculating weight and balance is really the same as your basic high school math class. Take the example below to warm up your brain and get in back into math mode if its been a while since you were in a high school math class. After that, go ahead and watch the video above and follow along while taking notes to work through the example weight and balance problem.
Example: If there is a box 1 foot from the pivot point and a box three feet from the pivot point, and the box three feet from the pivot point weighs 50lbs, how much does the box 1 foot from the pivot point need to weigh to balance the beam?
Answer: 50lbs x 3′ = 1′ x (some weight)
50×3 = 150 (means the box three feet away is acting upon the beam with 150FT-lbs of force, and the other box being only 1 foot away would need 150lbs to equal the 150ft-lbs.
If box X was 2 feet away from the pivot point it would need only 75lbs.