Dressing

Dressing

Thanksgiving was heavy. Heavy on the tryptophan and heavy on the fun. I am still adjusting to being awake for hours at a time. After eating two Thanksgiving dinners, in the same day, anyone would be tired! But there was also something else that was heavy and it was in the dressing bottle.
It is common knowledge that different densities of a fluid separate over time. People encounter this a lot in their kitchen, whether it is peanut butter, salad dressing, or the leftover fat and oil on a cooking pan. But did you know that the little flecks of pepper, paprika, poppyseed, or other particulates each have different bouyant forces. And it can be calculated if the values of ρ fluid and volume of object are known.
More amazing is the idea that when you squeeze that bottle and the dressing pours out there is a low velocity and high pressure at the bottom of the bottle but at the opening there is high velocity and low pressure. And you know what has no pressure, a VACUUM!
Although I was a very tired boy during the second feast, I was happy to know that I almost created a vacuum, in the sense of pressure. Twice! (two salads in one day)

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Banking

I know I shouldn’t be taking pictures while driving, but it was a beautiful sun. Sadly my phone is has a poor quality camera, something like 1 megapixel (I don’t actually know). Anyways I was driving on this curve of Nimitz Highway near Zippy’s (I think) and always wondered why the road tipped one way as it went from one bend to the next. I always assumed it was the ground underneath that had that shape, basically I thought the construction workers were lazy and just laid down asphault anywhere. But now I know that construction workers are brilliant and amazing, they specifically banked the turn, or angled the curve inwards towards the center, so that cars will not drive off course.

Nimitz Highway

Nimitz Highway

If the curve had been flat and not banked then car would have to slow down to go around the bend safely. The frictional force which provides the car its stability on a banked turn would only work if it were greater than the centripetal force. μmg > (mvv)/r. But since the highway is banked the car would not have to tremendously slow down. Friction is accounted for again. Imagine Nascar and you get the idea of why banking is, so very important. I now have a greater respect for construction workers, but I have read that there has been slight miscalculations in many banked turns due to inefficient tools that could calculate the proper banking necessary. I hope we can easily solve this problem to decrease crashes.