Todays date is August 31, 2012. This experiment was done last week. My name is Ashley. The other people in the group are Liz and Gabbie. A hypothesis was not needed for this lab. The purpose of this lab was to try to get five pipets to sink and then come back up (float) in a certain order. (12345, 54321).
The independent variable is the mass added to the pipet. The dependent variable is the rate the pipets sink/float in the water. The pipets float because their density is less than one. In order to make the pipets sink pressure has to be created. In order for them to float the pressure has to be released.
The materials used in this lab were water, five pipets, a 2-liter bottle, five different sized washers, and tape. Make sure the bottle has a cap. There were no safety concerns with this lab. The first step is to take the bottle and fill it with water, the more water in the bottle the easier the lab will be. Next fill up the pipets with water about 3/4ths of the way up. After that tape a washer on each pipet then put them in the bottle. Once they are all in put the cap on tightly and apply pressure by squeezing the bottle. The more pressure appplied, the faster the pipets will sink. Then release the pressure and the pipets will come floating back up. When they go down and come back up it should be in the 12345, 54321 order.
Here is a diagram of the experiment.In conclusion, the purpose of the experiment was to make the pipets sink and then float in a specific order. The pipets could float when just sitting in the water because they have less density than water. Water has a density of 1gram/mL. The pipets could sink when the bottle was squeezed becuase the pressure pushed more water into the pipets causing them to be denser than the water. The pipets sunk at different rates because mass of the different sized washers caused all of the pipets to have a different density. Another way to change the rate the pipets sink is by changing the amount of pressure applied, the more pressure the faster they sink. This experiment worked because of Pascal's principle which states that the pressure applied to a fluid spreads throughout the entire fluid. Another thing that works because of Pascal's principle is a hydrolic car lift. A few errors were made in this lab. Some errors in the lab included putting too much water in the pipets which caused them to sink when put in the bottle, poking the bottle to make the pipets sink, shaking the bottle to make the pipets sink, not putting enough tape on the washers and having them fall off in the bottle, and putting too little water into the bottle. Without a lot of water it is harder to make the pipets sink. To improve the experiment I recommend putting in enough water to almost completely fill the bottle.
