Aluminum Boats
Have you ever wondered how a ship made of steel can float? If you drop a steel bolt in a bucket of water, the bolt quickly sinks to the bottom. Then how can a steel ship float? And better yet, how can a steel ship carry a heavy load without sinking?
It has to do with the density, or the mass per volume, of the ship (and its cargo) compared to the density of water. In this science activity, you will make little "boats" out of aluminum foil to explore how their size affects how much weight they carry and how this relates to the density of water.
It has to do with the density, or the mass per volume, of the ship (and its cargo) compared to the density of water. In this science activity, you will make little "boats" out of aluminum foil to explore how their size affects how much weight they carry and how this relates to the density of water.
Image Credit: Teisha Rowland, Science Buddies / Science Buddies modified by Mrs. J
Materials
- Aluminum foil
- Ruler
- Tape
- Scrap piece of paper and pen or pencil
- Rag or paper towels
- Clay balls (or pennies, or something with some weight)
- Calculator
- Optional: Dry rice and measuring cup
- Bucket, tub, sink, or dishpan
- Water
Instructions
- Cut two squares of aluminum foil, one twice as big as the other. You could make one be 12 by 12 inches (or 30 centimeters [cm] by 30 cm), and make the second square be 6 by 6 inches (or 15 cm by 15 cm).
Image Credit: Teisha Rowland, Science Buddies / Science Buddies
- Fold the two aluminum foil squares into two different boat hulls. Try to make them the same shape. For example, you could make them both have two pointed ends (like canoes) or you could make them square or rectangular (i.e., rectangular prisms).
- Make finishing touches to the boat hulls. Make sure they do not have any holes. If needed, use a little tape to make them stronger. Flatten the bottoms of the hulls. On each, try to make sure the rim is the same height going all around the edge of the hull.
- Calculate the volume of EACH boat hull. If both hulls are rectangular prisms, you can measure the length, width, and height of each hull and multiply these dimensions together to get its volume. If parts of the hull have an irregular shape, measure the volume piece-wise and then add these volumes together. Use triangles to approximate any areas of the hull that are curved or angled.
Image Credit: Teisha Rowland, Science Buddies / Science Buddies
- Fill the plastic tub with some water.
- Take one of the boat hulls and carefully float it in the container of water.
- Gently add one clay ball at a time. To prevent the hull from tipping, try to carefully carefully balance the load as you add the clay balls. Slowly does it!
- Keep adding clay balls until the hull finally sinks.
- Carefully take out the sunken hull and place it and the clay balls on a paper towel. Dump any excess water back into the container.
- Count how many clay balls the hull could support before sinking (i.e., the penny that sank the hull does not count).
- Repeat this process with the other hull. Be sure to only add dry clay balls.
- Make sure that the volume you calculated for each boat is in cubic centimeters (cm³). Convert it if necessary. Tip: Cubic centimeters are the same as milliliters (mL).
- Convert the number of clay balls each hull could support to grams. To do this, multiply the number of clay balls by 3.5 grams (the weight of a single clay ball). How many grams could each hull support? Add this to your sheet.
- Fill in your Challenge Sheet with your findings!
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