Science & Mathematics - 14 November 2007

can they be used over again

2007-11-14 10:25:34 · 2 answers · asked by Anonymous in Other - Science

1.Why are some chemical symbols so different from the names of the elements that they present?
2. Why do some symbols have one letter, some have two letters, and some have three letters?

2007-11-14 10:23:16 · 4 answers · asked by Quinn H 2 in Chemistry

A. 5(x^3)^4 (3x^2)

B. (x^4-4x+3)/ ((√x)+1)

The answer for A. is:
180x^13 + 30x^13

The answer for B. is:
(2√x ((√x)+1)(4x^3-4) - x^4 - 4x+3) / ((2√x)((√x)+1)^2)
I'm not sure how to get the answers! Please help!!

2007-11-14 10:23:15 · 3 answers · asked by NEpatriots12 2 in Mathematics

A mechanical door opener is used to deliver a constant 65 W of power to a spring with k = 759 N/m for 3.5 s. If the spring was originally uncompressed, what is the compression of the spring (in centimeters) at the end of that time period?

2007-11-14 10:22:37 · 1 answers · asked by Anonymous in Physics

I had to do a few problems. I'm just checking if they are right. Thanks.

2x = 26
x = 13

4x = -12
x = -3

6x = 72
x = 12

8x = 808
x = 101

10x = 130
x = 13

12x = 360
x = 30

3x = 99
x = 33

6x = 96
x = 16

2007-11-14 10:21:00 · 8 answers · asked by Anonymous in Mathematics

2007-11-14 10:19:13 · 2 answers · asked by Anonymous in Chemistry

i'm doin ma hw and i take the volcano thing and so i choosed the a Ruiz,COlombia so it says here type of magma and silica content,

2007-11-14 10:18:14 · 2 answers · asked by Ankhaa G 1 in Earth Sciences & Geology

can anyone show all the steps to work out what x is equal to??

3( x/2 + 7 ) = ( x/5 + 2 )

2007-11-14 10:15:52 · 11 answers · asked by Anonymous in Mathematics

2007-11-14 10:15:09 · 16 answers · asked by shocker0204 1 in Botany

2007-11-14 10:14:58 · 1 answers · asked by Anonymous in Mathematics

I'm doing this science project, and I picked Aye-aye as my topic. One of the questions is 'Who are its predators?' but it doesn't say much on Wikipedia or Google. I don't know if it says, or if I just missed it, or if it has any at all?? Can anybody please help me out and include sources? Thanks!\

2007-11-14 10:14:42 · 0 answers · asked by ツ Petar 4 in Zoology

I saw a figure given in a magazine recently, but it looked a bit off and was only to the first 5 figures. I calculated it more precisely by hand, since my calculators won't deal with so many digits. I just wanted to check my calculations with anyone else who has done it. To get a precise answer, one must know the precise speed of light in miles per second and the precise number of seconds in a year. The figure in the magazine is a bit high because it evidently used 365.25 days for a solar year. That is only an approximation, as a bit of research on century adjusments of the Gregorian calendar will show.

2007-11-14 10:14:25 · 8 answers · asked by miyuki & kyojin 7 in Astronomy & Space

A lamina has the shape of a closed region bounded by the graphs of x^2 + y^2 = 4 and x + y = 2, and has the density
p(x,y) = x*y. Write the iterated integral for the moment of inertia about the y-axis. Then evaluate the integral.

I am unsure about how to write the bounds for this, I suppose you could use polar form and write r=2, but I am not too sure how to go from there if that is the case in terms of bounds etc. to set it up properly.

2007-11-14 10:11:03 · 1 answers · asked by offycakes 1 in Mathematics

i found a spider on my rain boot and i dont know what kind it is. it is black and resembles a black widow. the only difference is it has two dots rather than an hourglass. when we tried to put it in a glass it curled up and it hasnt uncurled. does anyone know what kind it is

2007-11-14 10:10:09 · 3 answers · asked by Sonna E 2 in Zoology

Suppose you were a packaging engineer.Explain why you might want to know the total are of all the faces of a rectangular box.

2007-11-14 10:09:15 · 5 answers · asked by @(3x!$ 2 in Mathematics

i dont want the answer to this as much as i need a clear step by step method of how it is done, and why any important stages happen. my question is

y = (e^-t)sin 2t

show y is a maximum when t = 1/2 arctan 2

i know that dy/dt = 0 when y is a maximum
and i got dy/dt = (e^-t )(sin 2t + 2cos2t)

but dont know if that last bit is correct. assuming it is, i still don't know where to go from here?

2007-11-14 10:07:59 · 3 answers · asked by martin r 1 in Mathematics

Solve the problem by using systems of equations.

2007-11-14 10:06:30 · 6 answers · asked by sue m 2 in Mathematics

1) nitric acid + potassium iodide ------> potassium nitrate + nitrogen monoxide + water

2007-11-14 10:02:44 · 1 answers · asked by Caramel 2 in Chemistry

2007-11-14 10:00:24 · 5 answers · asked by kaynat A 2 in Chemistry

2007-11-14 10:00:10 · 9 answers · asked by sherice p 1 in Astronomy & Space

Given the same sample statistics, which level of confidence will produce the narrowest confidence interval?

10 Points to best answer.

a. 90
b. 95
c. 85
d. 75

2007-11-14 09:59:41 · 1 answers · asked by deanjp 2 in Mathematics

A 6.5 L sample of nitrogen at 25±C and 0.76
atm is allowed to expand to 13.0 L. The tem-
perature remains constant. What is the ¯nal
pressure?
1. 0.063 atm
2. 0.38 atm
3. 0.75 atm
4. 0.12 atm
5. 3.0 atm
0

2007-11-14 09:55:59 · 3 answers · asked by Anonymous in Chemistry

and its ratios with subatomic particles?

2007-11-14 09:55:19 · 3 answers · asked by Anonymous in Physics

The combustion of acetylene gas is represented by this equation:

2C2H2 + 5O2 --------> 4Co2 + 2H2O2
(sorry that subscripts don't work)

a) How many grams of CO2 and grams of H2O are produced when 52.0g C2H2 burns?

b)How many grams of oxygen are required to burn 52.0g C2H2?

c)Use the answeres from A and B to show that this equation obeys the law of conservation of energy.

MY ANSWERS
a)175.78g CO2
35.98g O2
211.76g total

b)6.14g O2

c) ?

WHAT I DID
* means multiply, / means fraction

a) How many grams of CO2 and grams of H2O are produced when 52.0g C2H2 burns?

5.20g C2H2 * (1 mol C2H2 / 26.04g C2H2) * (4mol CO2 / 2mol C2H2) * (44.01g Co2 / 1 mol CO2) = 175.78g CO2

52.0gC2H2 *( 1 mol C2H2 / 26.04g C2H2) * (2 mol H2O / 2 mol C2H2) * (18.02g H20 / 1 mol H20) = 35.98g O2

= 211.76g total

b) How many grams of oxygen are required to burn 52.0g C2H2?

52.0g C2H2 * (1 mol C2H2 / 26.04g C2H2) * (5 mol O2 / 2 mol C2H2) * (32.00g O2 / 1 mol O2) = 6.14g O2

2007-11-14 09:55:01 · 2 answers · asked by Emily A 3 in Chemistry

and they want to know alll about fresno california!!

2007-11-14 09:51:11 · 10 answers · asked by mirage 3 in Astronomy & Space

what if an astronaut shoots a gun, does the bullet travel just like on earth, or does it float like the astronaut??

2007-11-14 09:50:53 · 27 answers · asked by David C 3 in Astronomy & Space

Solve this linear programming mixture problem: A small stereo manufacturer makes a receiver and a CD player. Each receiver takes 8 hours to assemble, 1 hour to test and ship, and earns a profit of $30. Each CD player takes 15 hours to assemble, 2 hours to test and ship, and earns a profit of $50. There are 160 hours available in the assembly department and 26 hours available in the testing and shipping department. What should the production schedule be to maximize profit? What is the maximum profit?

I've got:

x being the stereos
y being the CD players

theres 160 hours for assembly so
8x+15y<160

theres 26 hours for shipping
x+2y<26

Then
x>0 and y>0 as givens
How do I graph the feasible region?
I don't have a graphing calculator =[

2007-11-14 09:50:38 · 2 answers · asked by Anonymous in Mathematics

2007-11-14 09:47:57 · 4 answers · asked by Anonymous in Biology

2007-11-14 09:46:09 · 4 answers · asked by damigurl05 1 in Biology

2007-11-14 09:46:07 · 6 answers · asked by Anonymous in Medicine