The density is a physical property of each element that remains the same no matter how large or small the object. Density is expressed in terms of weight per volume, such as pounds per cubic inch, ounces per cubic inch, grams per cubic centimeter or kilograms per cubic meter. You can manipulate the density formula from density equals weight divided by volume to weight equals density times volume so that you can find the weight with the density.
Look up the density of the object if it is not given to you in the problem. You may be given a density chart or asked to use the periodic table if you are using a pure element for the problem. For example, the density of copper is 0.321 pounds per cubic inch.
Fill a beaker with enough water to cover the object. Note the volume of water in the beaker and then place the object in the beaker and note new volume.
Subtract the beginning volume from the ending volume to find the volume of the object. For example, if the volume of just the water was 3 cubic inches and after the object was placed in the beaker the volume increased to 3.5 cubic inches, you would subtract 3 from 3.5 to get a volume of 3.5 cubic inches.
Multiply the density by the volume to find the weight. In this example, you would multiply 0.5 cubic inches by 0.321 pounds per cubic inch to find that the weight is 0.1605 lbs.