Monday, September 10, 2012

mass, volume and density 1

To find the volume of an irregular shaped object, you can use the steps that we used in my science class to find the volume of a classmate.
Step 1. Fill a large container with water (we used a large trash can)
Step 2. Make sure there is something around the container, to catch any water displaced (We used a kiddie pool.
Step 3. Fill the container with  water as close to the top as you can. Be as precise as possible.
Step 4. Slowly lower the person into the water, make sure to minimilize movement to avoid splashing. Make sure that they are covered head to toe in water.
Step 5. Now again slowly lift the person out of the water, make sure they get as much water out of their clothes as possible.
Step 6. Have large graduated cylinders on hand (ours were 10,000ml), then use cups or scoops to transfer the water from the pool to the cylinders.
Step 7. When you fill your cylinder, empty the contents back into the original container. Make sure someone is recording how many cylinders you fill.
Step 8.  Make sure that your measurements are cubed, like you normally would when finding volume.
Here is who we measured.....




Finding the mass of an object is much easier (provided you have the appropriate tools). We just used a balance that the school provided, here is what they look like (Make sure not to confuse them with a scale)....


Once you have measured for mass and volume, you have a few more steps to go to find density.
Step 1. Divide mass by volume.
Step 2. Remember to use appropriate labeling at all times, poor labeling can often hinder results. The number that you get after dividing mass and volume is your density. If your mass was in kilograms and your volume was in centimeters, then your answer should look like this. X= kg/cm3.

To explain how density works you can use a partical diagram, to show how the particles in an object expand or contract. Here is an example of a particle diagram



Density can also be showed through a layering experiment, stacking liquids on top of each other. Here is an example of the layering experiment I did, as you can see the most dense liquids are on the bottom and the least dense are on the top.
Another good way to show density is through a candy bar test, try floating two candy bars in water and see what happens. I used a Snickers bar and a 3 Musketeers (fun size)
Top: 3 Musketeers
Bottom: Snickers
As you can see the Snickers is on the bottom, and the Three Musketeers floats. In one of the tests in my class we also used a Twix, at first it sank and then rose back to the top (about an inch under the surface) that is called flinking.

If you wanted to find the volume of a regular shaped object you can use this formula; sorensensci@gmail.comV=LxWxH/Mass=density

Well that should give you a little insight into density, the tests are super fun and extremely helpful.

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