Wednesday, August 5, 2015

Which Hurts More?

212° F
Let's play a little game. I'll list a bunch of possible actions. Each action will have 2 variations, (a) and (b). You choose either (a) or (b), depending on which would be safer (or less painful). Each of the questions will involve an oven hot enough to bake a cake (350° F), and a pot of boiling water (assume we're at sea level). So... would you rather:

1.
    (a) Stick your hand in the oven
    (b) Stick your hand in the boiling water
  ... for a period of 10 seconds


2.
    (a) Leave a fork in the oven
    (b) Leave a fork in boiling water
  ... for a period of 15 minutes. Then hold the fork tight with your bare hand.


3. Fill a jar to the top with cool tap water. Then:
   (a) Place the jar in the oven
   (b) Place the jar in the boiling water
  ... for a specific, but unknown, period of time. Then remove the jar and put your hand in it.


First see if you can figure these out yourself. They shouldn't be too hard. If you have trouble, heat up your oven and boil a pot of water, and see for yourself what hurts more. (NOTE: I take no responsibility for any resulting injury.)

My solutions to the questions are: 1.a 2.b 3.a. Now answer this: is boiling water hotter than an oven? Or is the oven hotter?

As with any problem, the answer depends on the meaning of the question. In this case, the answer depends on the definition of "hot". If the definition of "hot" is "having a high temperature," then the oven is clearly hotter, because water boils at 212°.

That's boring, though. Let's try another definition from the online Merriam-Webster dictionary: "capable of giving a sensation of heat or of burning, searing, or scalding." Or in other words, "burns when touched."

What's hotter now? Let's try each question. In question 1, the boiling water is hotter. This is because the water burns a lot worse when you stick your hand in it.

But in question 2, the oven is hotter, because it gives a greater sensation of heat (via the fork). This is because the temperature of the oven is higher than the temperature of the boiling water; given enough time, the fork can slowly reach 350° in the oven, but will only reach 212° in the water.

In question 3, the boiling water is hotter. It quickly heats the jar to a temperature of 212°. The oven also heats it; however, unlike in question 2, the oven is not capable of heating it above 212°, because the water will boil away before it gets that hot.

As you can see the situation affects what we perceive as hot; sometimes, things feel hotter than they really are, and other times, things feel cooler than they really are. The reason for this has to do with how quickly the heat is transferred into our skin. If the heat is transferred slowly enough, an object with a temperature of hundreds of degrees might feel barely warm. This effect is what happens inside an oven, because air is not a good conductor of heat. On the other hand, if heat is transferred quickly, a much cooler object may feel much hotter. This is the case with the boiling water - although it has a temperature of only a couple hundred degrees, it can cause severe burns if it spills on skin.

This principle results in some weird consequences.

For example, a couple days ago I was changing the transmission fluid in my dad's car. After draining the black oil into a pan, I accidentally dropped a metal socket extension into the liquid. After a couple of minutes carefully tipping the container back and forth, trying to isolate the piece, I finally reached in and pulled it out.

The oil felt soothingly warm. As I wiped the oil off of the socket extension, however, I realized the metal piece was burning hot. The oil had heated it to the point where it was painful to hold.

I'd had no idea how hot the oil was. If somebody had asked me, I would have said it was warm. But after feeling how hot the bolt was, I knew what was really going on.

Sometimes our senses can deceive us, and we perceive a reality that is much different from what it really is. Humans simply aren't perfect. Which is why scientists rarely rely on one person's observations or calculations when attempting to prove or disprove a theory, and why testimonials aren't nearly as trustworthy as experimental analysis.

With a little knowledge and experience, though, people can learn about their weaknesses and compensate for them. So step outside a little, and try some new things. Maybe shove your hand in a pot of boiling water. Don't worry - it's not as hot as it feels.


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