Question

Imagine that you have just bought your first home and one of it amenities is a built in ironing board. The base of the ironing board is hinged to a wall in a cupboard and it lowers from a vertical to a horizontal position when you open the cupboard door. Unfortunately the only support for the board is the hinge, which locks it in place. You quickly find that the board needs more support, so you want to add legs directly under the center of mass. The weight of the board is stamped on its underside. How would you used common household items (like a bathroom scale) to find the center of mass of the non-uniform ironing board? You must draw a free-body diagram when answering this question.

Answer 1

Place a stick or dowel between the bottom of the ironing board and the scale. The setup should be arranged so the stick is vertical and supports the board in the horizontal position. The indicated weight will change as you move the stick to different points along the bottom. It will be higher near the hinge and lower farther from the hinge. When the indicated weight equals that of the board, you are supporting the board under its CG (or at least at a distance from the hinge equal to that of the CG).