September 19th, 2016

How can a ship like the Titanic float, but a pebble sink?

This was our scientific question last week. We investigated this by placing a ball of Plasticine in a bowl of water and observing it sinking to the bottom. We then took that same ball of Plasticine and molded it into a shape that would float.  We then had to work in groups to design a boat with a sheet of tinfoil and see which boat would hold the most marbles before it sank.
Here are the results:
Minecrafters: 17 marbles
Pokemons: 6 marbles
Emojis: 7 marbles
Septic Eyes: 45 marbles (wow!)
Neons: 7 marbles
We learned that  when a boat floats, it pushes aside (i.e., displaces) water to make room for itself. But, the water around the boat pushes back. And the more water a boat displaces, the more force there will be pushing back on the boat. This force supports the boat. Boats that displace a lot of water can generally carry a heavier load than boats that displace only a little water.
We concluded that big boats hold more marbles; strength—sturdy boats don’t crumple under a load; and stability—wide boats don’t roll over as easily as narrow boats.