Go Ask Your Father: Straws, Pink Stuff, Christmas Trees, and A Fly In The Truck


dad's work

I’m loving the questions this week. Very science oriented. Physics to be exact. There are a couple of science YouTubers I already follow (VSauce and Veritasium). However, thanks to this week’s questions I found Physics Girl. She made a really neat, easy to make, electric “train” using a coil of copper wire, an AA battery and some neodymium magnets. I’ve always been science oriented. I enjoyed physics class in high school, though I wasn’t nearly at the top of my class. I was lucky if I was in the lower middle average kid in class. So to have kids who are as equally interested in science makes me happier than a astrophysicist with a super nova.

1. How does milk come up the straw when I suck on it?

I’ll forego all the sucking jokes, for the moment. Believe it or not, you are not pulling the liquid up the straw when you suck. It is getting pushed up from the bottom. When you suck on a straw you pull the air out of the upper part. This creates a low pressure area. The relatively high pressure (I say it’s relative because the pressure in the bottom of your milk cup changed only in relation to the space inside the straw) in the bottom of your milk cup pushes up. It’s the opposite of blowing into a straw to shoot a piece of corn. If you blow air into it, air pressure build up until the corn flies out and hits another kid in the head and you make a trip to the principal’s office. With a low pressure above the liquid in the straw, the liquid on the bottom rises to fill the space. The longest straw you could theoretically use is 10.3 meters. However, I’m not sure you suck enough to create a perfect vacuum required to use such a big straw. Speaking of vacuums… A straw will not work in outer space because you couldn’t change the air pressure because there is no air pressure. It will work inside a space ship, aka the Space Station.

2. What’s that pink stuff in the humidifier?

It could be my loofah, but it’s not. This stuff grows on the ledges in the tub, on the shower curtain, and in the humidifier. It’s pink. It easily washes off with cleaner. Then it comes right back in a week or less. It’s not mold. It’s an airborne bacteria. Don’t get all freaked out and panic, though. The science world calls it serratia marcescens. The rest of us call it a harmless nuisance. No matter what you use to clean it, it will return as it is airborne. It thrives in damp places (hence the growth in humidifiers and showers). The best you can do is clean to manage, not clean to rid. Make sure you ventilate the bathroom sufficiently during and after your daily scrub. If your like most normal households with young kids, the bathroom door is always open, anyway. No place is sacred.

3. Why do we set up Christmas trees?

Why exactly do we bring the outdoors inside? It’s so Santa knows where to leave all the presents, of course. I can only imagine how confused he might be in a house without a tree. Where do the presents go? According to History.com we have 16th century Germans to thank for the tradition of decorating the tree. Ancient peoples believed the evergreens would ward of witches and evil spirits during the months of little day light. They would decorate their rooms with boughs of holly along with pine and spruce branches. Christian Americans of the 1600’s thought it an odd tradition. Some even went as far as creating laws against it’s observance. Until Queen Victoria and her German Prince, Albert appeared as a drawing in the Illustrated London News in 1846. Much like today, if it was good enough for the royals, it was good enough for the people. It only took a few hundred years for it catch on.

4. If a fly were flying in the truck and stopped flying would he hit the back window?

I was grinning from ear to ear when Bang, the 6 year old, asked this question as we pulled into the driveway one afternoon. What a question! Imagine holding a baseball while riding down the road (someone else is driving). Toss the baseball up and catch it and to you it appears to have gone straight up and straight down. To the hitchhiker on the side of the highway that ball flew in an arc, a rainbow, a parabola. What about a fly, though? Thanks to YouTube, I discovered an answer. A dude flew a drone in the back of his van while his wife drove. As his wife slowly accelerated the drone stayed with the van. It didn’t drift to the back like I expected it to. However, with all the doors and the hatch open the van drove off and the done stayed put, effectively exiting the van without moving. It turns out that the drone provides sufficient downward force to keep it stationary inside the van when all it’s doors are shut. However, with the doors open, it has nothing to push against so it can’t remain inside. Would a fly, which doesn’t have nearly the same force as a drone, have the same effect? Or if it stopped flying would it smash into the back windshield? Like trying to drink through a 10 meter straw, that would really suck (for the fly).

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