I was curious about gamma ray burst in general, and supernova is one possibility, hypernova too but the closest hypernova candidate is IIRC 3 thousand light years from Earth and no-one believes this will cause a problem either. I would again like to consider the worst case scenario though and...
Dr. Barb Mattson is a good friend of mine (You should see her awesome Daisy the Model A page on Facebook) but generally is too busy to help me with these kind of things. I know she's a world-class X-Ray Astronomer though! My thought though is how dangerous could a "dark menace" be. I know a...
Folks,
I'm struggling to write a monograph that details the potential of a rotating supernova directing a gamma ray burst directly at the solar system such that it would strip the Earth of most of its OZone and rain high-energy gamma radiation upon all terrestrial life, similar to as...
It's because Santa Clause is your Parents:
Ah, xkcd -- has an answer for everything! Thank you Randall.
But, for the record, I agree with thrust and momentum being the critical components; though it doesn't mean the Bernoulli principle isn't real.
Thanks! :)
So I agree that we're probably in the Region III range for a car although clearly when velocities are really small there are no doubt other rather complex drag equations since Cd is not constant in the Region I and Region II regimes, but as you point out this 0.0167 mph is barely...
Thanks Hikaru!
Interesting. But, working in another direction, let's assume that for a given velocity, Cd is constant for a sphere since that is a fully symmetrical shape (which as we can see is empirically calculated to have a drag co-efficient of 0.47). It's interesting to note that the...
Okay, thanks Hikaru and K2 for your help on the accelerated drag problem. Now I have another drag related problem I wonder if you you help me with.
Say a car is put in a wind tunnel and is measured to have the following attributes:
Frontal Area: Ax
Side Area (Right): Ay
Frontal Coefficient of...
Not to belabor a dead (time) horse here but I was curious what would arise if we instead assumed the car was traveling quadratically between samples. I'm not asking for help this time, just doing a thought experiment that I though I'd share with the group. This should also illustrate hikaru...
It's a very simple text based spreadsheet, time in seconds in column A, velocity in mph in column B. This is given 1. Given 2, we know the car evaluated under this test procedure is estimated to have a total range of R miles. From this information, calculate this car's power function...
And of course, this means more generally:
And now it all seems to make sense! Can you very smart Physicists confirm my conclusion? I appreciate y'all letting me know if I finally got it right! :)
Thank you Hikaru and K^{2} for trying to help!
So what I'm trying to do is take the EPA test suit known as USSD or LA4 and get a more accurate estimate of the power used by a car in that test suit. Or, more specifically, to find the average power for each interval and multiply back by the...
Yes, yes, I know how the Power-Force relation is derived. But I'm talking specifically drag where v is not constant and is averaged over an interval of the form:
1 sec | 4 m/s
2 sec | 6 m/s
3 sec | 6 m/s
4 sec | 5 m/s
etc.
Obviously there is some acceleration component between each...
Okay, so I think I got it now. The average power required to overcome drag is therefore given by the equation:
P_{drag,average} = \frac{1}{6} C_{d} \times \rho \times A \times \left( \frac{\Delta s}{\Delta t} \right)^{3}
Does that sound right? And doesn't that just become...
Thank you kindly, hikaru! Glad to know my knowledge of basic Physics isn't completely shot. So going back to the original problem of Drag, clearly the instantaneous drag on an object is given by the standard formula:
P_{drag, instant} = \frac{1}{2} C_{d} \times \rho \times A \times \nu^{3}...