Discussion in 'Science' started by HereWeGoAgain, Jan 29, 2018.
Not thunder but you're going the right direction.
The lower limit for human hearing is about 20 Hz. Brain waves when awake range from 3.5 to 14 Hz and higher, but mostly under 20 Hz. And interestingly there is a transition from theta to alpha waves at 7.5 Hz.
You might say that 7.5 Hz is the center frequency, which is really interesting.
F = dP/dt --> the rate of change of momentum is equal to the force applied. As soon as you let go, the momentum, hence the velocity begins to change. But mamooth got it - thermodynamic motion; the motion of atoms and molecules due to temperature. This can for a tiny fraction of second, counter the force of gravity by providing a net upward momentum.
And the rest you mentioned have been answered. There is a list at the top of the previous page.
Thunder is mostly in the 100 HZ range but can occur below 20hz . After a quick search, so cheating a little bit, came across a book (nearly 1000 pages long!) about the physics of cloud formation where it describes hailstone spin being in the range of 9 HZ which gives rise to the unique shape of hailstones though appears to be based on theory rather than measurement.
Haha, maybe to be fair I need to narrow it down a bit. It is an electromagnetic phenomenon. Just as are brainwaves.
Perhaps the stroke/return stroke cycle in a lightning strike?
Not the lightning...
I think those frequencies would be a little higher than those in question.
I would say bicycles. They return much more of the potential energy gained going uphill than walking.
How about roller skates? Or ice skates (but I don't know they can be considered a common form of transportation.)
Aerodynamic lift caused by the reduced air pressure caused by the hot coffee heating the air above it.
According to this web site it requires .6 kcal to walk one mile at 2 miles/hr
and .32 kcal to bike one mile at ten miles/hr.
One gallon of gasoline is 32,000 kcals.
If a car engine gets 50 m/gal, it takes 160 kcals/m,
so bicycling is indeed about 600 times more efficient.
I'm not good with calories - it seems like there are some tricky elements there that I haven't bothered to figure out.
I'm not doubting your result, though. Your answer is far better than was mine.
Maybe, but the bicycle isn't Candy Apple Red and can't go 100mph while carrying 2 girls
<major flashback to teen years>
Bicycles it is! It is the most efficient form of transportation.
Already answered: Thermodynamic motion but not for the same reason. Random biases in the motion of particles can result in an upward momentum for a fraction of a second.
And slightly more efficient than in line skates which is slightly more efficient than ice skating, it turns out.
Question 13: What is this phenomenon?
A professor once asked on a test
"How can you determine the height of a building using a barometer."
There are at least 8 different ways to do this. Which ones can you think of?
The "green flash" seen sometimes at sunset over the ocean.
Separate names with a comma.