8,597 reputation
1730
bio website en.wikipedia.org/wiki/…
location United States
age 71
visits member for 3 years, 9 months
seen 2 hours ago

BS Mechanical Engr.
PhD CS(AI)
CS Prof (4yr)
Numerous consulting jobs.
15 yr at http://www.pharsight.com
Published book on CS & several articles
4 kids, 2 grand
Pilot(student)

P.S. The picture is a Beta-prime distribution. It shows the program speedup factors you can get if you see a problem twice in 2, 3, 4, and 5 samples.


1d
comment Sounds of supersonic objects
@LDC3: I think you are saying your original answer was incorrect. You might want to edit it.
1d
comment Is this a case of the “venturi effect”? What's behind the “Venturi effect” actually?
My understanding is that the Bernoulli equation is not about conservation of energy, but conservation of momentum ($F=ma$). The only way a fluid (or any mass) can change velocity (accelerate) is by experiencing a force (pressure difference). Wikipedia
2d
comment How do we know the boundaries of a wavelength?
@red888: Up to you. It's not too hard to slide a vertical line cursor to the peak of a curve so it looks, by eye, to be in the center of a peak - and it's the place where a tangent to the curve is horizontal.
2d
comment Question about Elon Musk's Hyperloop Suspension
That link says: "an electrically driven inlet fan and air compressor would be placed at the nose of the capsule in order to "actively transfer high pressure air from the front to the rear of the vessel," resolving the problem of high speed transport in a tube that is not a hard vacuum" and " A fraction of the air is shunted to the skis for additional air pressure, augmenting that gained passively from lift due to their shape". So all the air in the process comes from the tube and remains in the tube, even though it is at low pressure.
Jul
2
comment Does a person inside a falling bus fall to the front of it?
Suppose the fall is 100m. That comes to a fall of about 4.5 seconds, so speed at the bottom is around 45m/s. I suspect terminal velocity for a nose-down falling bus is a lot more than that.
Jul
1
answered How do we know the boundaries of a wavelength?
Jun
30
comment Flow Rate Calculation from a drain tank through a pipe
In case it's not clear, you have to break it into a few problems: 1) What is the resistance to flow at the orifice, and that depends strongly on the shape of the orifice, how it is tapered, etc. 2) What is the resistance to flow in the pipe. 3) If there are bends in the pipe, what is the resistance due to those? Those resistances all give pressure drop as a function of velocity, and you know the total pressure drop, so you have to solve for the velocity. From that you get the flow rate.
Jun
30
comment Can a photon have little to no energy and/or speed?
@Daniel: You're absolutely right. I'm trying to keep it simple for an OP who is clearly a newbie to physics.
Jun
30
answered Can a photon have little to no energy and/or speed?
Jun
30
comment Can a photon have little to no energy and/or speed?
Its energy is a function of its frequency (color) not of its speed.
Jun
30
comment Can a photon have little to no energy and/or speed?
When photons go through a material, like glass or water, they travel more slowly. There are materials in which they can go very slowly. But that does not reduce their energy.
Jun
26
answered Why do the tangent holes (like in pitot-static tube) feel the static pressure?
Jun
26
comment Simple Beam Worst Case Scenario
You can figure it out. Hint: Try moving F all the way over to P1 or P2.
Jun
24
answered Water pressure on a floodlight in a swimming pool
Jun
24
comment From Civil Engineering undergrad to Physics grad
I'm afraid you're not going to get a satisfactory answer. I had undergrad in Mechanical Engineering and Master's without designation, having done the work in M.E. and Civil Eng. I wanted to get a PhD in Computer Science, specializing in Artificial Intelligence. I eventually did that, but not from a top-tier school, although I was able to do the research at a top-tier school. The difficulty was I did not have the coursework considered standard. So from my viewpoint, it can be done, but you are the only one who can figure out how.
Jun
24
comment Direction of pressure forces on a control volume (surface)
@FredikLAa: To help you understand, 1) assume the velocity is 0, and 2) assume the volume is a cylinder with a piston on the right. The fluid is pushing out, and to keep it in place, the piston is pushing in. Then, convince yourself the velocity doesn't matter - i.e. there can be leakage in the left and out the right, and it doesn't change anything.
Jun
23
answered Direction of pressure forces on a control volume (surface)
Jun
23
comment Why wasn't the moon visible during the day a few decades ago?
@Kyle: You need to see it when the moon is in a phase such that there's a good bit of it to see, and that determines the angle at the viewer between the moon and the sun. At half-moon, for example, the angle is $90^0$, so if the moon is high in the sky, the sun is low. On the other hand, if the moon is full, the angle is $180^0$, so you can't really see both at the same time (if there are any obstructions around you like trees or buildings).
Jun
20
comment Is it possible to make a low dense object sink in a fluid of higher density by cutting the object in particular shapes?
Aren't you just describing a suction cup?
Jun
19
comment Drift of Earth's orbit?
+ ... "Wagnerian doom" :)