Science & Mathematics - 17 December 2007

1. A coin is placed 12.5 cm from the axis of a rotating turntable of variable speed. When the speed of the turntable is slowly increased, the coin remains fixed on the turntable until a rate of 36 rpm is reached, at which point the coin slides off. What is the coefficient of static friction between the coin and the turntable?

2. A 1100 kg car rounds a curve of radius 70 m banked at an angle of 12°. If the car is traveling at 90 km/h, will a friction force be required?
If so, how much force? (Enter zero if there is no friction force.)

Estimate the force a person must exert on a string attached to a 0.110 kg ball to make the ball revolve in a horizontal circle of radious 0.600 m. The ball makes 1.80 revolutions per second. Do not ignore the weight of the ball. In particular, find the magnitude of FT, and the angle it makes with the horizontal. [Hint: Set the horizontal component of FT equal to maR; also, since there is no vertical motion, what can you say about the vertical component of FT?]
FT = N
= °

2007-12-17 08:36:05 · 1 answers · asked by Shawn Carter 1 in Physics

Their are a lot of egg drop questions on here but their are none where the only thing you can use is wood
the requirments:
All wood no paper or cardboard
no thinker that the width of a popsicle stick

i need help i cant think of any ideas
lightest mass wins
egg will be supplied at the start of class

2007-12-17 08:35:17 · 1 answers · asked by bucket71 2 in Engineering

2007-12-17 08:34:06 · 1 answers · asked by britney♥ 2 in Physics

What I am wondering is why do cars parked in the carport when it is cold outside not get frost on thier windows while cars parked in the open do? Even cars parked a few feet away still get frost while the cars under the carport stay clear.

2007-12-17 08:32:39 · 3 answers · asked by Max L 2 in Weather

Why can't there be a homomorphism from Z_16 onto Z_2 cross Z_2? Please explain

2007-12-17 08:32:05 · 10 answers · asked by Jamanski 3 in Mathematics

i need to no

2007-12-17 08:30:55 · 9 answers · asked by u dont need to kno! WTF!!! (: jk 1 in Weather

I want to know what animal sweats for research. I would love any answer.

2007-12-17 08:29:30 · 16 answers · asked by miranda 2 in Zoology

fridge is to cafeteria as A cell is to a nucleus. HOW?

2007-12-17 08:28:58 · 3 answers · asked by Jo M 1 in Chemistry

i need so solid info on the mettal copper. not where to get them.if you have good sights then can you give the site please

2007-12-17 08:25:55 · 4 answers · asked by jam4u06 2 in Chemistry

not the latin word hydrargyrum but the word "mercury" itself

2007-12-17 08:25:50 · 4 answers · asked by ooh-taay 2 in Chemistry

2007-12-17 08:24:08 · 9 answers · asked by Anonymous in Mathematics

2007-12-17 08:22:10 · 3 answers · asked by deathkill749 1 in Engineering

2007-12-17 08:18:51 · 2 answers · asked by Anonymous in Chemistry

2007-12-17 08:18:23 · 9 answers · asked by Mark S 3 in Mathematics

given the following information:
1) I used 9.586g of steel
2) The specific heat for the steel is 0.447 joules/g deg. C
3) I put the steel in 65 ml of water
4) the temperature of the water started at 22 deg C and ended at 41 deg C
5) the only equation that I have is calorie= mass X change in temperature X (cal/ g degrees C)
6) 4.18 joules = one calorie.

2007-12-17 08:18:00 · 1 answers · asked by Luke H. 1 in Chemistry

hello! :)

Can anyone tell me why phosphorus trichloride has a low melting point ( - 92°C ) a boiling point ( 76°C ) ?

Thanxx a lot!! :D

2007-12-17 08:17:49 · 2 answers · asked by in luv with rock^^ 1 in Chemistry

2007-12-17 08:17:02 · 11 answers · asked by Boogie 2 in Mathematics

A certain radar installation used to track airplanes transmits electromagnetic radiation of wavelength 7 cm.
a) What is the frequency of this radiation, measured in billions of hertz (GHz)? ANS: 4.2857GHz
b)What is the time required for a pulse of radar waves to reach an airplane 6 km away and return? ___s (note: it is not 2x10^-5)

2007-12-17 08:13:37 · 3 answers · asked by TheLostOne 3 in Physics

Curve C has the equation
y=(x-1)(x^2-4)

It cuts the x axis at the points (-2,0)(1,0)(2,0)

y=x+7 is an equation of the tangent to C at the point (-1,6)

The tangent to C at the point R is parallel to the tangent at the point (-1,6)

find the exact coordinates of R.


Impossible really.

xx

2007-12-17 08:11:23 · 3 answers · asked by Anonymous in Mathematics

1.What is the effect of a base on an acid?
2.What is the effect of an acid on a base?

thanks

2007-12-17 08:10:23 · 2 answers · asked by Anonymous in Chemistry

find a continuous function in [0, infinity) that is in L1 but not in L2.

2007-12-17 08:10:12 · 1 answers · asked by N 1 in Mathematics

and yes i have solve the rubiks cube many times over and over....just give me new easy notation...

2007-12-17 08:09:31 · 3 answers · asked by viperdc742 1 in Mathematics

thank you for you help!

2007-12-17 08:07:11 · 2 answers · asked by wildstudent 1 in Chemistry

Let (X, M, m) be a mesure space and let f_n be a sequence of integrable complex valued functions that converges uniformly to a function f. If m(X) < oo, then, f is integrable and lim Int f_n dm = Int f dm. I found a somewhat different proof for this, but some pepole says its too complicated. Do u agree?
Fix some eps >0. Since f_n --> f uniformly, there exists k such that n >= k => |f_n - f_k| < eps => |f_n| < |f_k| + eps, which implies the k tail of f_n is dominated by |f_k| + eps. Since |f_k| is integrabel (because f_k is) and m(X) < oo, then Int (|f_k| + eps) dm = Int |f_k| dm + eps m(X) < oo, so that |f_k| + eps is integrable. Since the k tail of f_n also converges to f, it follws from the Dominated Convergence Theorem that f is integrable and lim(n >= k) f_n dm = Int f dm, which shows the k tail of Inf f_n dm --> Int f dm. Hence, lim Int f_n dm = Int f dm as stated.

There's another proof for this theorem that doesnt rely on the D. C. Theorem.

2007-12-17 08:03:44 · 2 answers · asked by Steiner 7 in Mathematics

to melt down their for a long time.

2007-12-17 08:01:09 · 14 answers · asked by Anonymous in Zoology

do you know about a lead?

if you are good on it, could you answer these questions?

1.what toys contain lead?
2.lead's history
3.lead's chem/physical proportion
4.why is Pb toxic?
5.Summarize: Advice Santa why he should/should not give their toys to the children?

2007-12-17 07:59:11 · 1 answers · asked by Anonymous in Chemistry

3 Calculus Questions, Multiple Choice, Please Help, Pictures included! click links for problems...
I always give out best answer points

3 questions

Question 1

http://i106.photobucket.com/albums/m254/meskodaclown/calchelpmeeee1.gif



Question 2

http://i106.photobucket.com/albums/m254/meskodaclown/calchelpplease2.jpg



Question 3

http://i106.photobucket.com/albums/m254/meskodaclown/pplleaseehelp33.jpg


Thank you so much! Some details / explanations to the solutions would help me out a lot for my future test as well... Thanks..

2007-12-17 07:54:35 · 4 answers · asked by calcconfusion 1 in Mathematics

2007-12-17 07:54:31 · 6 answers · asked by Anonymous in Biology

OK I'm doing a research project and I need some info. I'm doing my project on the element "Sodium". Who discovered this element and when? Where and How was it discovered and is it an old element? If it is an old element please tell me some information about it a long time ago. And also is there any other uses besides salt? Thanks!! Please answer!! Don't answer one part of it though, try and answer the whole thing it's really important!!!

-samantha

2007-12-17 07:52:25 · 5 answers · asked by Sam 2 in Chemistry

yesterday??

2007-12-17 07:52:21 · 2 answers · asked by clavdivs 4 in Physics