Water Lost Through Breathing, Part 2

In the last post we talked about the water loss from breathing and used the assumptions of exhaled air being at 92 deg F and 90% relative humidity, and inhaled air close to freezing, to develop a constant to estimate the water loss per hour for any breathing rate. This time, we’ll look at the effect of temperature and relative humidity and elevation on that constant.

Water Lost Through Breathing

Have you ever wondered how much water you lose by breathing? Do you think that it is more or less than that lost through sweating? Most of the time when we breathe, we are exhaling moister air than we breathe in. There might be a few exceptions, but normally our bodies are losing a little bit of moisture with every breath. In this blog, we’ll try to quantify that moisture loss, at least in a ballpark way. 

Tire Heating on Landing, Part 2

In the last post, we talked about the moments of sliding/rolling motion when a tire first contacts a surface with a mismatched velocity.  Using the assumptions and simplifications outlined in that post, today we will make estimates of heat generation at the tire/runway interface, and temperature profiles inside the tire material based on a hypothetical airplane landing scenario.

Tire Heating on Landing

When an airplane first touches the runway, there is an interesting moment of drama because the ground (relative to the airplane’s wheel) is moving past quite rapidly, while the wheel just at the instant of touchdown, is not moving at all.  Of course, there is a great deal of friction between the non-rotating wheel and the moving ground, so the wheel is accelerated rapidly in rotation until it “catches up” to the ground speed and rolls without sliding.  However, the wheel has some rotational inertia and so requires a little bit of time to get up to speed.  During that time, the tire is sliding across the ground and generating a lot of heat. Today we’ll talk about a rough approximation for the heat generated and transferred to the tire during an airplane landing.

Heat Transfer in the Kitchen, Part 3

This will be the third (and final, at least for now) post about heat transfer in the kitchen.

Heat Transfer in the Kitchen, Part 2

Last post we were talking about heat transfer in the kitchen and we’ll continue exploring that topic today.

Heat Transfer in the Kitchen

When I tell people (and by 'people', I mean 'non-engineers') that my field of specialization is heat transfer, I usually get some incredulous response on the theme of, "There is a whole field where someone would study nothing but heat transfer?" with the implied sub-text of "sane someone" accompanied by lots of extra question marks.  I have to admit that in everyday experience, most people don't have to think quantitatively about heat transfer.  However, almost everybody connects (non-quantitatively) with heat transfer in the kitchen, so in this post we'll explore heat transfer in cooking.