Science & Mathematics - 27 October 2007

Four railroad cars, each of mass 2.80 104 kg, are coupled together and coasting along horizontal tracks at speed vi toward the south. A very strong but foolish movie actor riding on the second car uncouples the front car and gives it a big push, increasing its speed to 4.15 m/s south. The remaining three cars continue moving south, now at 1.80 m/s.

2007-10-27 06:41:05 · 1 answers · asked by Anonymous in Physics

2007-10-27 06:39:35 · 2 answers · asked by M.Hassan A 1 in Mathematics

I'm a machinist and I need to make a precision reflective surface, I can put a mirror on it, but I'm not sure how accurate it would be. But I know I can machine and grind a surface with a mirror finish. Will this be comparable to a mirror though?

2007-10-27 06:38:02 · 6 answers · asked by Ivan G 1 in Engineering

first i can be wrong because i am 14.my question is why cant we turn oxyzen in solid?we can turn oxyzen liquid by an extrem force like freezing.then why cant we turn it into solid? and is there any thing or power or energy which is more faster than light?and why? if i have done any wrong thing please dont insult me.and if you liked my question you can give me a star.thanks to everybody and pls answer this question.

2007-10-27 06:35:45 · 7 answers · asked by Anonymous in Physics

A merry-go-round of radius R, is rotating at constant angular speed. The friction in its bearings is so small that it can be ignored. A sandbag of mass is dropped onto the merry-go-round, at a position designated by r. The sandbag does not slip or roll upon contact with the merry-go-round.
Rank the following different combinations of m and r on the basis of the angular speed of the merry-go-round after the sandbag "sticks" to the merry-go-round:
1.) m =10kg, r=.50
2.) m =40kg, r=.25
3.) m =10kg, r=.1.0
4.) m =20kg, r=.25
5.) m =10kg, r=.25
6.) m =15kg, r=.75

2007-10-27 06:34:31 · 3 answers · asked by Nik 1 in Physics

2007-10-27 06:34:16 · 2 answers · asked by waisps 1 in Astronomy & Space

how do the physical and chemical properties of the elements change?

2007-10-27 06:26:58 · 2 answers · asked by LeylaWayla. 1 in Chemistry

what are some unique things about pond ecosystems?
and/or
what are some predator interactions

2007-10-27 06:23:41 · 2 answers · asked by massiekur 1 in Botany

Alright, I was watching a TV show last night and they were showing how pills are made. My question is, where do the chemicals that make the drug come from? Street drugs are easy. Cocaine comes from the coca plant, heroin from the opium poppy. Some prescriptions are easy also. Penicillian comes from mold. But, where do these new drugs come from? Like the cancer drugs or AIDS drugs or any of the blood pressure or cholesterol drugs? Are there just millions of chemicals out there and if you mix different combos they do different stuff? Or do most come from plants? If anybody has any links or any insight, please share. And please, no stupid answers.

2007-10-27 06:23:07 · 1 answers · asked by Scott B 4 in Medicine

1. The entropy of the Universe increases for all natural processes.

2. If two bodies are in thermal equilibrium with a third body, then they are also in thermal equilibrium with each other.

3. Ein - Eout = ΔEsystem

4. It is impossible to construct a device that, operating in a cycle, will produce no effect other than the extraction of heat from a reservoir and the performance of an equivalent amount of work.

5. It is impossible to construct a device that, operating in a cycle, will produce no effect other than the transfer of heat from a lower-temperature reservoir to a higher-temperature reservoir.

6. The total entropy of an isolated system that undergoes a change cannot decrease.

2007-10-27 06:22:51 · 2 answers · asked by Anonymous in Physics

i am 13 years old and people are always telling me how smart I am because I learned to read when I was 13 months old, and that I understood M-Theory when i was 7, stuff like that, Also I am really interested in science, but I've no desire to work in that field, I understand time travel and I have built small machines that can exceed my own running speed since i was about 9, what are the qualities of a person like Newton or some of those other really smart people? I need to know how old some of you people are, and how old you were when you started showing signs of being smart! And dont tell me I am the only one here who is under 30 and understands M-Theory because @ my school I have teachers that dont get it!

2007-10-27 06:22:25 · 11 answers · asked by shacka t 2 in Physics

On a cold morning, when the sun was hot and the wind cold, I could see the shadow of my head steaming out!!
Is that dehydration? Evaporation of my body's liquids? Someone said it was my body loosing it's warmth...
What was it?

2007-10-27 06:22:18 · 6 answers · asked by anya 1 in Weather

james, matthew, and raymond each have a favourite subject at school. the subjects the enjoy are science, mathematics, and drama. use clues to match each boy with his favourite subject. 1.raymond and the student who enjoys mathematics are on the school basketball team 2.matthew does not enjoy working with chemicals 3.raymonds favourite subject starts with the last letter of his name

2007-10-27 06:20:09 · 3 answers · asked by Anonymous in Mathematics

what keeps natural ponds from growing?

2007-10-27 06:19:46 · 1 answers · asked by massiekur 1 in Botany

2007-10-27 06:18:13 · 13 answers · asked by wesley l 1 in Mathematics

2007-10-27 06:18:10 · 5 answers · asked by Joffrey L 1 in Mathematics

2007-10-27 06:17:22 · 1 answers · asked by gong 1 in Botany

2007-10-27 06:16:48 · 6 answers · asked by Anonymous in Zoology

I have to help someone do a research paper and these are the 2 questions she can't find answers to.Any websites would be appriciated.

2007-10-27 06:15:28 · 3 answers · asked by pntnmrmansmom 2 in Astronomy & Space

2007-10-27 06:15:04 · 24 answers · asked by chatman6969692003 1 in Chemistry

Does increasing mass increase speed of projectile?
Does increasing mass increase distance forever?
How does the increased force from the added mass transfer throughout the entire system?

2007-10-27 06:11:47 · 2 answers · asked by Anonymous in Physics

I understand that we can be hit by asteroids without warning!

2007-10-27 06:09:52 · 3 answers · asked by superdave 1 in Astronomy & Space

http://i24.tinypic.com/2q1hqia.jpg

I need to learn how to solve the problem above. And I really want to learn how to do it, not just the answer. Can someone please help explain it to me?

2007-10-27 06:09:28 · 9 answers · asked by ... 1 in Mathematics

2007-10-27 06:08:11 · 3 answers · asked by latishalanding 1 in Botany

http://i24.tinypic.com/24gvn0p.jpg

I need to learn how to solve the problem above. And I really want to learn how to do it, not just the answer. Can someone please help explain it to me?

2007-10-27 06:06:58 · 4 answers · asked by ... 1 in Mathematics

A projectile has mass 21 kg and is fired at a 60 degree angle above the horizontal with a speed of 80 m/s. At the highest point of its trajectory, it explodes into 2 pieces, one of which falls straight down with no initial speed. The 2 pieces have equal mass, and air resistance can be ignored. Find the distance from the point of firing that the other piece strikes assuming a level terrain, and find how much energy was released during the explosion.

2007-10-27 06:02:49 · 2 answers · asked by Red_Wings_For_Cup 3 in Physics

How come I remember when I was a kid, on rainy days there would be tons of worms crawling on the pavement. Now on rainy days, I never see ANY. What's up with that?

2007-10-27 06:02:04 · 17 answers · asked by Anonymous in Earth Sciences & Geology

Why do physicists continue to pursue answers to sigma when if you use Eeinstiens theories and equations rather than the outdated Newtonian gravitational equations, there is no need for Dark Matter ot explain sigma at all.

2007-10-27 06:00:32 · 4 answers · asked by DannyB 2 in Physics

2007-10-27 05:57:22 · 4 answers · asked by Opal 1 in Biology

2007-10-27 05:53:57 · 17 answers · asked by realitycheck 3 in Parapsychology