7,738 reputation
1628
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 3 years, 3 months
seen yesterday

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.


Dec
16
comment If an airplane is flying sideways, is it in free fall?
@Vivek: There's a maneuver called a knife edge where the wings are at 90 degrees to the ground. What the rudder does is put the fuselage sideways to the wind, generating the lift that holds the aircraft against gravity. Generally any such use of the rudder is called a slip or skid.
Dec
16
comment If an airplane is flying sideways, is it in free fall?
@Vivek: Yes, but would you call it free-fall? The pilot could be pulling 4G or more in that horizontal direction.
Dec
16
answered If an airplane is flying sideways, is it in free fall?
Dec
15
comment Can the weight of a bird be measured, considering air friction?
@Santhi: It comes out as extra air pressure on the bottom of the box. The wings get lift by pushing air downward, which hits the bottom of the box, which pushes the air back up so it stays in the box. That means the bottom of the box is feeling more pressure.
Dec
14
revised Calculate speed from accelerometer
added 3 characters in body
Dec
11
comment Does juggling faster less work then juggling slower?
Before you hoist a ball to a height, it falls into your hand from the same height, so in principle it takes zero work for any height. So it all depends on how efficient your muscles and joints are.
Dec
10
comment Where can I get fluidics components?
Excellent question, though some may think it is off-topic for physics. If I were you, I would start thinking about 3-d printers.
Dec
10
revised height of dam to allow certain flow rate
added 153 characters in body
Dec
10
answered height of dam to allow certain flow rate
Dec
8
comment How to approximate lag of roll of a bird (or RC airplane)?
@Yeti: You're probably only able to estimate an approximate value. There's guesswork no matter how you do it.
Dec
6
answered How to approximate lag of roll of a bird (or RC airplane)?
Dec
3
comment Gravitational field intensity inside a hollow sphere
I like Qmechanic's answer, but my own intuition is this: suppose the shell consists of a lot of small "moons" covering the shell. You could be close to one and feeling its gravity, and the ones "across" the way have gravity that falls off at $d^2$, but the number of them increases with $d^2$, so they are just as powerful as the one you are next to.
Dec
3
comment Calculating the force required to lift a weight with a screw
He's ignoring friction, so it's just an energy balance. The energy put into lifting the weight is what? 2000 lb * 1 inch = 2000 inch-lbs. That handle must be pushed 1260 inches to get the same energy, and 1260 inches * 1.6 lb ~ 2000 inch-lbs. What's this dimensional analysis you're talking about?
Dec
2
comment Why is a thought experiment a valid way to prove anything?
@Albalma: Next to Feynman's lectures, this is my favorite book on relativity. The author was teaching relativity in a continuing-ed class where people were math-phobic, so he does a great job of making it accessible.
Nov
30
comment Why is a thought experiment a valid way to prove anything?
@Albalma: I agree - dogmas and stigmas are bad things. I'm in favor of skepticism. Not only questioning of positive results, but questioning of negative results. A perfect example is "cold fusion". If on the other hand you're talking about global warming, skepticism is a good thing, but using it as an excuse to do nothing and just let the hammer fall is poor wisdom.
Nov
30
revised Create air stream from heat
added 56 characters in body
Nov
30
answered Create air stream from heat
Nov
30
revised Why is a thought experiment a valid way to prove anything?
added 294 characters in body
Nov
30
answered Why is a thought experiment a valid way to prove anything?
Nov
28
comment Why can't we fly?
We can fly