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location San Mateo, CA
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visits member for 3 years, 3 months
seen 7 hours ago

12h
answered Intuitive explaination for why higher engine compression ratio is more efficient?
12h
comment Intuitive explaination for why higher engine compression ratio is more efficient?
@Kyle: No, compression is a good thing even if combustion is complete in both cases. As Floris says, the heating makes much higher pressure after compression, which energy can be extracted.
21h
answered Fluid flow at mach 1
1d
comment What kind of mirror do i should use for rear projection?
If it is good in the center, you should recognize that you are close. You clearly want a convex mirror. Because the distances are small you might need an aspheric mirror and might need some lenses in the path as well. I'm sure there is software (that might be hard to understand) and consultants that can solve this easily if you give them the parameters. The components you need may not be the ones that are already on the market.
Jul
26
comment Is it feasible to detect light emitted from planet earth 2,000 years ago by reflection from an object situated 1000 light years away?
There is a huge difference between detecting total illumination and resolving images. Astronomers are detecting light echos of events, but there is a lot of integration (averaging) going on. You can get a (time convoluted) light curve, but resolving detail seems out of bounds.
Jul
25
comment Could two identical stars revolve around each other in a common orbit if we only account for Newtonian physics?
How close do they have to be for you to consider them identical? I believe similar mass binaries have been observed, but don't have a catalog at hand. The Hulse-Taylor pulsar is two neutron stars-that is pretty similar
Jul
24
comment Could two identical stars revolve around each other in a common orbit if we only account for Newtonian physics?
You are being ill-served by the remark that the earth revolves around the sun. That implies that there has to be something there to revolve around. In fact, all bodies of the solar system revolve around the common center of mass. Since the sun is so massive, it approximates the center of mass, which is where the remark comes from. Jupiter is about $1/1000$ the mass of the sun, so the sun-Jupiter CM is $1/2$ million miles from the center of the sun, which is slightly outside the sun. Does that meet your "observed?
Jul
24
comment Calculate the current in mA which will be flowing through the two resistors
You only list three resistors. There is no mention of a resistor in series. You are asked to calculate the current in the "other two resistors", the $3 \Omega$ and $5 \Omega$ ones.
Jul
24
answered Calculate the current in mA which will be flowing through the two resistors
Jul
24
comment can we get electrical energy from gravitational energy?
Note that a retrograde orbit does not have any higher orbital speed than a standard orbit. It will have a higher speed relative to the surface or the ambient magnetic field, but not a whole lot for a low orbit satellite. It is probably not worth the extra work of getting to a retrograde orbit.
Jul
24
revised How do heated showers/faucets work?
correct typo
Jul
24
comment How do heated showers/faucets work?
Yes, there is a water heater with a tank that keeps the water heated. Typical US home ones are 30-50 gallons (120-200 litres). Typical temperatures are 120-140F (49-60C). When you turn on the hot water, it takes a while to get hot because the water stored in the pipe between the heater and the shower has cooled.
Jul
24
answered How do heated showers/faucets work?
Jul
22
comment How to measure rainfall? And how is it determined for a specific location?
50 miles is an enormous distance. Near San Jose, CA, we have places within 20 miles that average 10 and 80 inches per year. Think Kauai, HI, which has Mount Waialeale, the "wettest place on earth" averaging 462 inches per year, while Poipu averages 30-40 inches per year. To my eye they are about 15 miles apart.
Jul
22
comment Potential Energy and Kinetic Energy
What are your thoughts? Have you looked in your book or done a search? You should find equations for some of these. Where are you stuck?
Jul
22
revised Why do bubbles make a sound?
add info
Jul
22
answered Why do bubbles make a sound?
Jul
21
answered Momentum acceleration in space?
Jul
19
comment Possible intergalactic celestial objects
My point is that I think all of these can be ejected from galaxies, but some will be hard to see at long distance. For weakly bound ones, you need to make sure that the tidal forces do not disrupt the system. When you do that, you may lose the outer reaches, but you may eject enough to count as whatever category you are interested in. Certainly we can't see asteroids outside the galaxy.
Jul
19
answered Possible intergalactic celestial objects