Weigh a small empty fish tank, then weigh it when full of water. One gallon of water suitable for tropical fish occupies 231 cubic inches and weighs about 8.57 pounds. Have students calculate the maximum height to which one can fill the aquarium and keep within the table's limit of 250 pounds. Students may also explore and draw diagrams of the possible base sizes of an aquarium that is filled to a height of 12 inches and can still be safely placed on the table. Determine the volume of water in the bathtub in gallons and the weight of the water.
Most people are surprised at how heavy water is.
If the maximum weight is 250 pounds, then it can hold no more than about 29 gallons, or 6700 cubic inches, of water. If the height of the water is kept constant at 12 inches, then the area of the base would need to be about 550 square inches, so students can come up with possible dimensions for the base, such as a square base measuring about 23 inches on each side. The water would weigh approximately 625 pounds. The water in the tub would fill four and a half aquariums of the given size, each containing water weighing about 143 pounds. The aquariums themselves would weigh an additional 21 pounds each.