Floating subs

Why do submarines float (and sink)? It's all a matter of controlling the sub's density. If the submarine is less dense than water, it will float. If it is more dense, it will sink. So let's start by looking at density. In words, density is how much stuff is in a certain amount of volume. Mathematically, density is as follows:

(Side note: if you were to measure density on the Moon, another planet, or deep in the ocean, you'd have to worry about the difference between weight and mass. Fortunately, for most people reading this post weight and mass are approximatively equivalent. For more information, check out this link.)

We're also in luck...water has a very easy density to remember: 1000 kg/m^3. Ocean water is slightly different due to it's salt content, but for our purposes we're just going to ignore some of those subtle nuisances.

When a submarine is floating on the water, its ballast tanks are filled with air. So let's pretend the bottle below is a submarine with air-filled ballast tanks and measure it's weight.

Next the volume of the bottle needs to be deterimed. Normally this would be done by sticking the whole bottle into a graduated cylinder filled with water, but I do not have one. So I estimated the number of teaspoons that the bottle held with a measuring cup. There were about 78 teaspoons.

So now that we've found the weight and volume (and converted them to practical units), we can find the density of the empty bottle.

So here's the big question...will the bottle float?? Do you remember what we said about density up above?

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It floats!

It floats because the density of the bottle (601.5 kg/m^3) is less than water (1000 kg/m^3).

Next let's fill the bottle with blue water and see what happens. We already know the volume, but we need to find the new weight.

With the new weight we can find the density of the bottle filled with blue water:

So, is the bottle with water going to float?

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No!

The bottle sank because its density of 1573 kg/m^3 is more than that of water.

Can you figure out how full the bottle should be so that it will hover in the water?

Here are some more interesting links:

How Stuff Works

MSI learning lab

Friday: scavengers

Today I felt like a scavenger. Ben and I went to Laura's for dinner as she was trying to get rid of some food. It was delicious. Then we got to empty her refrigerator and ended up taking home two coolers worth of food. It was very good timing because we haven't gone to the grocery store for a while and so had lots of room for more food.

I think I'm most excited about the frozen precut chicken. I have realized several times in the past few years that I enjoy eating smaller sized foods more than larger sized foods. If something fits into my mouth without needing a knife (or a bite) that makes my life much happier. (A good example of this is tortilla chips. I enjoy the crumbs and Scoops better than large triangles.)

Thursday: lunch

I had lunch with Jess today. It was really the highlight of my day because work was so busy...it was nice to have a break. It's really nice to just get outside, away from the cold air conditioning, and spend some time relaxing with a friend.

Tuesday: a few more upsides to working a long day

Today was a long day at work. However, there were two good things that happened:

1) I was able to pass off fixing some WIPs to someone else because I'm too busy. SCORE!!!

2) Around 6:45 all the phones started ringing. I was out on the manufacturing floor...a phone was ringing. That phone stopped and a different phone started. I went to my office. Two phones were ringing. They stopped. Another phone rang and someone picked it up - no one was on the line. The fax machine buzzed. My phone rang (there was no one there). Another office phone rang. I went back to the manufacturing floor and the phones were still ringing. When I left 20 minutes later the phones were still all abuzz. Interesting.

What was also interesting is how we all have the same type of phone and yet they all sounded different.

Monday: 5 question Friday

1. What is one thing you miss the most about childhood?

I miss having summer vacation. Even in high school when I was working I still had a lot of time off. It was wonderful to have a change of pace.

2. Are you still friends with your friends from high school?

Yes, but we aren't nearly as close as we used to be. Probably because I don't live close to any of them anymore. I do keep in touch with several of them though and see them occasionally.

3. Is there a catch phrase, cliche, or word that just drives you bonkers every time you hear it?

"My bad." Bad is an adjective, so you can't own it.

4. What is one thing that you think symbolizes America...besides "Old Glory"?

This picture:

5. Do you have any scars? If so, what's the story behind it?

I have one on my back from where I had a mole removed.

(Thanks to Five Question Friday for the questions)

Sunday: why I am (semi) happy to pay my taxes

Do I like paying taxes? Not really. Does it seem unfair that those who make a lot of money have to pay more taxes? Sure. Do I think the money could be handled better? Yes. But today I don't want to talk about such topics tonight. Today I want to refute the comment "I've never heard anyone tell me anything good that taxes have done for them."

Taxes pay my salary. Taxes actually pay a lot of salaries when you think about it.

Taxes pay for schools. Even if the schools aren't very good learning is still important.

Taxes pay for recycling.

Taxes pay for a lot of social services...some that keep me safe (I can pretend it's like insurance) and some help out people who are having a hard time.

In conclusion, while taxes do have several downsides, they also do have some positive effects on society.

Sunday: cooking frisbees

We looked in our car today only to find that all of our four frisbees were misshappen.

Since it is nice to have a lot of Frisbees, we're hoping that we can reshape them. I placed one in hot water for a while to see if it would come back. It is still a little off, so it is currently under a 40lb bag of salt. The Frisbee did cool down before I put it under the salt bag, so I might need to retry the process again later.