The diagram below shows a uniform bar supported at the middle point O. A weight of 40 gf is placed at a distance of 40 cm to the left of the point O. How can you balance the bar with a weight of 80 gf?
To balance the anticlockwise moment of 40 gf, we should place the 80 gf to the right of the middle point.
Using principle of moments, 40 gf×40 cm=80 gf×x
∴x=20 cm