Floating & Sinking

When it comes to talking about things that float and things that sink there is one answer we always is true. We know that rocks will sink and wood will float. Is this always true? The question is do we always know that rocks are going to sink and wood is always going to float. I hate to be the bear of bad news but sometimes they lie to you. Not all rocks sink some do float and not all wood floats it does sick. 

This is Pumice rock. This is one type of rock that floats.

Pumice rock comes from a volcano it is formed after a volcano's force pushed air into the rock. That makes the pumice very light. It usually floats for a while, when water gets into the rock it starts to sink a little.


As we observed and watch our professor drop a ton of rocks and a ton of wood pieces into water we got to understand many things. When we watched the rocks go clear to the bottom we immediately decided all rocks sink. Then he did the same thing with the wood but all the wood float. They he through in  one piece of wood and one rock but they did total opposites. How does that happen?
In rocks we know that there are foam cells that are closed. Meaning water can't get into them when immersed in water. When closed cells are filled with air the density of a rock can be less than waters density. Meaning the rock will float. This is the same concept with wood.  
Remember that an object will float if it less dense than the liquid it is placed in. An object will sink if it is more dense than the liquid it is placed in. 

We learned many things in class and also got to experiment in for ourselves by making a boat out of certain materials. We were given six straws, aluminum foil, and tape. We had to figure out how we were going to make the boat float. We we made our boat we tested it in the water by putting metal washers on top. Our group got to 45 washers on top before our boat gave out and took in water. So, after that was done we tried to make a new boat but with same material. When we did it the second time we only got 38 washers on it before it took water and sank. We tried just two ways but there were many options to getting our boat to hold multiple washers and still float. 

On Friday we tried to get a flinker meaning, we wanted it to float and sink half way. We didn't want it to sit on the bottom or float on the top. We wanted it to try and be in the middle of the water. Our group tried many things to get in the middle. We were super close but it just bobbed up and down. We tried many entrance point but was either to heavy or to light. We could not get the density right. After reading about our experiment remember yo can try many thing on your own with supervision on how to get certain things to float as well as sink. You can even try to get a flinker just like we did. Maybe you will have better luck than our group had. 

Picture Cited Lists:
I borrowed the picture from this website. https://www.universityofcalifornia.edu/news/solving-mystery-floating-rocks-pumice