A scale for rapidly weighing ingredients in a commercial bakery operation is shown. An empty bowl is first placed on the scale. Electrical contact is made at point A, which illuminates a light indicating the bowl's contents are underweight. A bakery ingredient, such as flour, is slowly poured into the bowl. When a sufficient amount is added, the contact at A is broken. If too much is added, contact is made at B, thus indicating an overweight condition. If the contents of the bowl are to weigh 18 lb ? 0:25 lb, specify dimensions h and d, spring stiffness k, and the unstretched length of the spring L0. The bowl and the platform on which it rests have a combined weight of 5 lb. Assume the scale has guides or other mechanisms so that the platform on which the bowl rests always horizontal.