# Search results

• Users: amt
• Order by date
1. ### Extrapolating Human Population to 5000 B.C

Yes I agree- But let's consider a linear extrapolation function based on statistics known in 2005, 1940 and 1750. Let's ignore abnormal population growth or population shrinkage due to war, famine, decease, weather etc.
2. ### Astrology Science Or Scam?

Extreme_machinations- You are on the right track. Educate the Masses.
3. ### Extrapolating Human Population to 5000 B.C

The Earth's current Human population is 6 Billion. Some time in 1940 the world population was 3 billion and around 1750 the population was about 500 million. Is there a scientific method to extrapolate the Human population for the date 5000 b.c? Thanks.
4. ### 'escape' velocity

But wait...there's more... Try throwing a stone high up in the air...it will fall back. Now try even harder- after a while it will fallback. Seems like the speed with which you throw, does not let it to escape the Earth's gravity. Now, let's say that you have developed super human...
5. ### What gravity waves?

Darn it! So let me get this- A body with Mass warps space. This warp is the result of the ripple effect when the body first appeared in space at that particular location. A good example is- placing a boat in a pond. The boat displaces water and sends out ripples.
6. ### What gravity waves?

The Laser Interferometer Space Antenna is supposed to be launched in 2013. This will be used to measure Gravity waves that is still resonating from the Big Bang (Article from DISCOVER magazine- August 2005 edition).
7. ### What gravity waves?

So, the only way I can comprehend gravitational waves is by thinking that they are continuous (oscillation as explained by you all). So is it correct to think of it as continuous ripples across space? though the frequency and speed of this ripple is still unknown?
8. ### What gravity waves?

What gravity waves? Considering Gravity is the warping of space, then how is gravitational waves possible? Aren't we all sliding down the slopes of space due to the massive warping of space by ojects? isn't space pushing us down? Then why is gravitational waves a topic? Thanks.
9. ### Howbout adding this to sticky?

Well that's now what I meant. I meant something like this. Simple: Fy | |\ |.\ |..\ |...\ |...\..T= 222N |...\ |...\ |...\ |...\ |___60_\____>Fx
10. ### The light in my oven

How about Planks constant and black body radiation? Don't they mean heat from light that is proportional to the frequency? This light thing looks stranger and stranger the more and more I learn about it. I was thinking about the ramifications of photons being effected by heat if that was...
11. ### Howbout adding this to sticky?

Seems like everyone student requesting help here fails to show a drawing of a free body diagram for all static/dynamic problems. Perhaps this should be made mandatory. A free body diagram is the first step to solving problems. This will also help them develop good problem solving skills.
12. ### The light in my oven

So, I was baking this Indian delicacy I got at the local Indian grocery store commonly known as 'samosas'. I switched the light inside the oven to observe the progress and then suddenly this thought occurred to me. What happens to light when it gets heated up? What does photons do under...
13. ### Microwave heating

Microwaves are bad for our bodies. They are so bad, they are being developed as weapons by the US military. It was a secret for a long time and soon to go into the field for the first time.
14. ### Solving the mass of the Earth using 17th and 18th Century tools

Several centuries ago, the radius of the Earth was found using the angles of the Sun rays formed on Earth. To find the mass you will probably have to use g=(G.m1.m2)/r^2. This means you will need the mass of another body, like the moon. Not sure how else you could find the Mass of the earth.
15. ### Finding the forces in equalibrium

Always post a free body diagram first. This makes things easy for both yourself and the rest of us trying to help. Wall |\ |.\ |..\ |...\ |...\ |...\ |...\ |...\ |...\ |...60\ --------- From this diagram how can you conclude that the vertical component is her weight? The...
16. ### Utility companies AC instead of DC?

If you want to transmit DC, then you will need a much thicker power line. DC povides low voltage/high current. If you convert P=IV, then to handle more Amps you need a thicker power line. For AC, you can transmit very little current. To compensate this a very high voltage is used- example...
17. ### Utility companies AC instead of DC?

Here is a good description for AC vs DC http://en.wikipedia.org/wiki/War_of_Currents
18. ### Having trouble with Torque HW Problems

Where are the drawings?
19. ### Need help solving homework problems

OK since none of the Physics gurus have responded, I am going to write my own calculations. But no guarantee this is correct. However, the answer looks good and reasonable. You should atleast get partial credit for this. Try to fully understand how the problem is broken into. |.....N |.....^...
20. ### Need help solving homework problems

Looks like E is the energy. 'omega' should be angular velocity. (1/2)mv^2 is the kinetic energy.
21. ### Need help solving homework problems

I will try to post something for problem-2. It's been awhile since I opened my Physics books. Perhaps someone else here might also offer some insight.
22. ### Need help solving homework problems

OK, I have still not figured out this yet. But since you have requested some teaching steps, here is one fundamental approach you absolutely have to know. This will help you with most physics problems. See the pushing force at 30 deg? Since this force is at angle it can be broken into 2...
23. ### Need help solving homework problems

For 2. Here is the free body diagram. Does it look correct? |wall | |<-----2 ft board------> |==================|\ |.....|... |.\ |.....|50 lbs...|30\ |.....|....|...\ |.....V....|...\ force pushing up is 30 degrees. Pushing is done to prevent to board from falling.
24. ### Need help solving homework problems

For 1. It says divide the larger one by the smaller one(ratio of the large one to the small one). The larger one is the one with mass = 2m. The smaller one is simply m. So- [(2/5)2MR^2] ------------- = 2 [2/5)MR^2]
25. ### Need help solving homework problems

For 1. You need to find the formula for the Moment of Inertia of a Sphere. I think it's (2/5)MR^2, but you might want to check. Now the problems says that one Mass is twice the other. Simple, make m1=m and m2=2m. Substitute this in the formula for Moment of Inertia and divide one by the other...
26. ### How to do logarithms?

Logarithms are used to make large number calculations in an easily comprehendible format. You have probably seen graphs showing a curved graph going from left to right. The smallest value on the left might be '0' and the largest value on the right might be 100,000,000. Now for example if you...
27. ### Finding Mass of Object without Scale

Yes, but how are you going to calculate the force with which you accelerate? you may still need a scale.
28. ### What is the purpose of resistance in a circut?

Bottom line is: It controls the flow of electrons. For example if you are sending 5Amps of current, then a resistor can be used to make this smaller-2Amps, 1Amp or even 1 milli-Amp as needed by any circuit.
29. ### Dynamics Help. My exam is on Monday

F=ma. A weight scale is one instrument along with the stop watch.
30. ### Particle accelerator

To accelerate 1 proton to 99% of 'c', how much energy is required? If the particle accelerator has a radius of 5 miles, how many revolutions has the proton got to make before achieving 99% of 'c'? Thanks.
31. ### Particle accelerator

So, according to Relativity, as an oject approaches the speed of light, it's mass increases and the Energy required to sustain the motion goes to infinity, basically making high speed travel almost impossible. How is it that Particle accelerators are able to accelerate Protons at 99.99% of...
32. ### Dynamics Help. My exam is on Monday

Is the acceleration you are going to find the average acceleration or Instantaneous acceleration? The runner could be changing velocity during his 100m sprint. This would suggest changing acceleration. Change in Velocity with respect to time is acceleration: a= dv/dt. If you want to find his...
33. ### Do scientists think black holes have singularities

I think black holes are obvious phenomenons. If you think 'escape velocity' then it seems much more realistic than simply stating 'black holes', as though it is some mysterious object. However the point of convergence or 'singularity' in a BH is quite speculative. They say that can lead to...
34. ### Why does EVERYONE claim voltage is electrical pressure?

I understand your frustration. Here is more : http://en.wikipedia.org/wiki/Voltage
35. ### Why does EVERYONE claim voltage is electrical pressure?

You need a pressure to push the electrons in a conductor. If not, what will force the electrons(current) to move? With no pressure(electro motive force or potential difference), the electrons will simply idle around at a small pace. Don't flip- But, think of the Ocean wave as the Voltage and...
36. ### Possible Explanations To Fermi's Paradox?

So for now we can conclude that we are alone and hence, we must celebrate life to the fullest! :biggrin: My theory: If we are alone, then we are the result of Intelligent Design. If there are others, then we are the result of Billions of years of on going evolution in a never-ending chain...
37. ### Electromagnetic Field, H vs. B

Yes- I apologize for my mistake. I just referred to some text. H=B/u, where 'u' is the permiability constant. The Electric Field should have been 'E'.
38. ### Electromagnetic Field, H vs. B

Gosh it's been so long since I studie EM in college. Difference between H and B is that, one is the Electric field and the other is the magnetic field. They always accompany each other perpendicular to each other. I am sure someone here will be able to post something more detailed. Until...
39. ### Can spacetime as a rubber sheet be taken literally or merely as pedagogic?

So, people down in their gravity wells would see us aging faster, and we would see them aging slower, provided that we could see each other over those distances. Now, does this mean that we are REALLY aging faster and that the people in the gravity wells are REALLY aging slower? Or is it...
40. ### Can spacetime as a rubber sheet be taken literally or merely as pedagogic?

I like the answers, especially the ones with formulas. Let me ask another question please. How different would our lives be if we lived in a gravity free place? Let's assume we live on a planet, but this particular planet does not warp space/time. Would our lives go by faster? Thanks.
41. ### Can spacetime as a rubber sheet be taken literally or merely as pedagogic?

The Rubber sheet analogy is an excellent source of example. It should be noted that, even though Mass warps space, the reason we are falling towards Earth is because Space is Pushing us towards Earth and not not because we are sucked into Earth. Here is a question I have on space-time...
42. ### The earths like shield

1- The magnetic field shields us from Nasty Solar flares. A good example of the magnetic field shielding us is the Aurora Borealis you see in the Northern Hemisphere. 2- The Earth's atmosphere is made up of several layers consisting of Stratosphere, troposphere, mesosphere, ionosphere etc...
43. ### Life Against All Odds?

From what we know now, there is no other life forms. We are alone in this Universe. Any counter debate is purely speculative. This is where believers in creation Triumph.
44. ### Life Against All Odds?

Even though there are 9 major planets and a Star, along with several dozen smaller moons, life would not have been possible without the Moon orbiting the Earth. This is the miracle of life and we simply need to celebrate our presense. The odds of life forming here in our solar system is very...
45. ### Density and wave absorbtion

I think Plank's constant plays a role here. Because, how much energy is absorbed will depend on the frequency of the wave passing through.
46. ### Why are orbits elliptical?

There is still no clear and concise answer to the original question though.
47. ### Infinite Galaxy

Do definte proof has been found yet as to the future of the Universe. Some say it will fall back on itself in the 'big crunch' and that would be the end.
48. ### Wavelength & Distance Relation in MICROWAVE

1-Yes there are SAR limits. I think the limit is something like 1.6W/KG in the USA. Getting too close to a high Watt transmitter can be very dangerous. I have heard of accidents and people getting seriously hurt. 2-Cellphones transmit at 1W of power. More than enough to transmit to about...
49. ### Blackhole question

From the diagram applet, it seems like the singularity bottoms out when the Mass=1. What's happening there? Is 1 some critical point?
50. ### Wavelength & Distance Relation in MICROWAVE

Higher frequencies make it easier to transmit. A good example: at the latter part of the 19th century, 2 different companies were fighting to make electricity. One with AC and the other with DC. The company making AC eventually won because the higher frequency makes electricity travel longer...