7,425 reputation
1628
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 3 years, 1 month
seen 15 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.


Aug
25
comment Gravitational acceleration at half Earth's radius
Don't you mean $r/R$ where $R$ is the outer radius of the earth, and $r$ is the radius you are at?
Aug
25
revised How to calculate pressure loss due to water leakage from a hole in a pressurized unit
added 838 characters in body
Aug
25
revised How to calculate pressure loss due to water leakage from a hole in a pressurized unit
added 838 characters in body
Aug
25
comment How to calculate pressure loss due to water leakage from a hole in a pressurized unit
@Mitchell: If you can measure $V_{air}$ then you can get your expression. A way to do that is to have a closed cylinder of known volume full of air. Then pump a known volume of water into the bottom of it, which compresses the air down to a known volume. Another way is to use a glass tube as a level indicator on the side of the cylinder. Another way is to put the cylinder on a scale, so you can measure how much water went in. No matter how you do it, you need to experiment.
Aug
25
comment How to calculate pressure loss due to water leakage from a hole in a pressurized unit
@Mitchell: You calibrate it. Set it to a pressure $p_1$. Then either measure volume $V_1$ of the air pocket, or let out a certain amount of water $\delta V$ and measure the decrease in pressure $\delta p$. Assuming constant temperature, Boyle's law just says $p_1 V_1 = (p_1 + \delta p)(V_1 + \delta V)$. You can solve for $V_1$ if you want to.
Aug
25
answered How to calculate pressure loss due to water leakage from a hole in a pressurized unit
Aug
25
revised spacecraft thrust through means other than liquid propellants
added 101 characters in body
Aug
25
answered spacecraft thrust through means other than liquid propellants
Aug
23
comment Airplane on a treadmill
The simplest way to answer this is to imagine replacing the wheels with frictionless skates (after all, that's what wheels are trying to be). Then you see that the premise of the question is not possible. Except for the implied drag due to spinning up the wheels, There's no speed the ground can be moving backward that prevents the plane from moving forward.
Aug
22
revised Simple mechanics problem
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Aug
21
revised Simple mechanics problem
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Aug
21
answered Simple mechanics problem
Aug
18
comment Calculate flow rate of air through a pressurized hole
The answer is right. Intuitively, if you want to double the velocity of the escaping air, you need to quadruple the pressure. The reason is that pressure (force) is momentum (of the air) per unit time, and if the velocity doubles, you're doubling the momentum of each parcel of air, and you're doubling the number of parcels of air.
Aug
18
revised Would a three wheeled vehicle be faster than a four wheeled vehicle of the same weight?
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Aug
18
comment Would a three wheeled vehicle be faster than a four wheeled vehicle of the same weight?
@Ben: It certainly does. The car starts with a certain amount of potential energy. At the end its kinetic energy consists of kinetic energy due to forward motion plus rotational kinetic energy of the wheels. The more rotational energy there is in the wheels, the less there is in forward motion. You could look at it as - the necessity to spin up the wheels acts as a drag on the car. The only possible effect of 3 instead of 4 wheels is fewer wheels to have rotational kinetic energy.
Aug
18
answered Would a three wheeled vehicle be faster than a four wheeled vehicle of the same weight?
Aug
15
revised Milk-First School
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Aug
15
comment Calculate flow rate of air through a pressurized hole
It has a strong dependency on the shape of the orifice. Check this out: Flow through an orifice
Aug
14
awarded  Good Answer
Aug
13
comment Why is the range for a particle thrown at 90 degree same as that of a particle thrown at 0 degree?
What is the angle measured against? The ground? What is the velocity of the projectile? How high above the ground is it when it is thrown? The question is still not clear.