What Floats your Boat?
- aluminum foil
- plastic wrap
Questions before starting:
- Does larger or smaller surface area float better? Why?
- Does boat depth matter? Explain.
- How does the pennies' placement affect the boatís buoyancy?
- 4) Which material do you think is most dense? Does this material float best or worst?
Procedures and Questions:
- Name some materials that boats are made of:
Wood, steel, plastic
Today, we donít have these materials; instead we have paper, aluminum foil and plastic wrap so we
can simulate these materials.
- What contributes to making things float?
Buoyancy, surface tension, weight, surface area/shape, density of liquid
- If you wanted to sink something, how would you do it?
Add weight, poke a hole, gather weight unevenly
For the contest, we will be testing your design by putting in pennies one at a time and
seeing how many pennies it can carry before it sinks.
- How do big ships prevent sinking from a puncture?
By creating different sections within the ship like compartments, so if one is punctured, water
will only fill that isolated compartment. The boat may be lopsided but it will still be able
Of course, the boats you will be building today wonít be this intricate, but we just wanted
you to think about this idea.
- Why does ice float in water?
Ice is less dense than water. When water freezes, it makes a crystalline structure between the
atoms, which makes the molecules more spread out. Therefore, there is less mass and a larger
volume, density equal mass over volume
So when youíre building your boat, think about the density (taking into consideration mass and
volume of your boat)
Now that we considered the affects of different boat materials and designs, let's think about
how things will float in liquids.
- Do you think your boat will hold more pennies when placed in water, oil, or rubbing alcohol?
Water will be the best because oil has very little surface tension (no attraction between the
molecules, cohesion). We know oil floats in water. Think about how when we make salad dressing
with oil, those oil molecules are separated and floating at the surface. Rubbing alcohol is
even less dense.
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