Last week I made a HUGE mess in class in the name of science. I did a demonstration to get the kids thinking about mass and gas. Since a lot of people assume that gases have no mass, I wanted to challenge their thought processes. Here is a video of my demo from last year as I didn't get a chance to record it this year :( After the demonstration, I explained how the it worked. Contrary to popular belief, gases DO have mass and when I added the baking soda to the vinegar, a chemical reaction happened that produced the gas carbon dioxide. Carbon dioxide has more mass than the mixture of gases (approximately 78% nitrogen, 21% oxygen, and small amounts of argon, methane, and even carbon dioxide) we breathe. As I poured the invisible gas into the bag, it caused the balance scale to tip to the side that had the gas with the higher mass and density (as it was more concentrated as it was poured out of the pitcher than the spread out molecules in the air). After discussing the scale activity, we reviewed some very important vocabulary: Matter- anything that has mass and takes up space Mass- the amount of matter in an object; in science we measure in kilograms, grams, etc. Volume- the amount of space an object takes up Density- the amount of mass packed into a given space (volume) Weight- a measure of the gravitational pull on an object; a force we measure in Newtons We also talked about the difference between weight and mass. Mass is the amount of matter in an object, and weight is the measure of the gravitational pull on the mass in an object. When talking about weight, we reviewed that gravity is a force that pulls objects toward one another. We discussed how we are pulled toward the center of Earth which is why we don't go flying off into space. We also talked about how the sun's gravitational pull keeps all of the planets in orbit around it. We also talked about how moons orbit their planets due to each planet's gravitational pull. We then had a brief refresher of fourth grade science and discussed the planets and their order from the sun. We discussed mnemonics to help us remember the order of the planets: My (Mercury) Very (Venus) Educated (Earth) Mother (Mars) Just (Jupiter) Served (Saturn) Us (Uranus) Nachos (Neptune). Another fourth grade standard is the comparison of the planets according to size, We can do this by comparing them to food :) We talked about how our weight would be different if we were to go to another planet, or even the moon. We'd still have the same MASS (all of our body would have the same amount of stuff in it), but the different gravitational pulls of the planets would have different effects on our mass, thus making us weight different amounts on each planet.
For example, if a child with a weight of 30kg on Earth were weighed on Mars (which has a gravitational pull that is only about 2/5 of Earth's), they would only weigh 11.3 kg on Mars. They still have the same amount of stuff (mass) in them, their mass just isn't being pulled toward the center of Mars as much as it is pulled toward the center of Earth. On Jupiter, that same 30kg child would way 75.8kg! The amount of gravitational pull a planet or other object has depends on its mass- the larger the object's mass, the stronger its gravitational pull. After these discussions, worked on calculating our weights on the different planets and Earth's moon. Here is a website that will let you do the same thing! Very cool! https://www.exploratorium.edu/ronh/weight/
0 Comments
Leave a Reply. |
Archives
June 2019
Categories
All
|