Science & Mathematics - 29 September 2007

Physical change may cause a change in form or state, but not in substance. Chemical change occurs when substance changes into one or more new substances with different properties.

2007-09-29 14:18:15 · 5 answers · asked by lavender 3 in Chemistry

2007-09-29 14:08:35 · 21 answers · asked by nathan c 1 in Physics

2007-09-29 14:05:59 · 4 answers · asked by ns 1 in Engineering

A jacks screw has Ideal Mechanical Advantage of 25lb, and a force of 40lb is applied to lift a load of 300lb. What load can be lifted by the machine if it is operated by a force of 60lb?

2007-09-29 14:03:04 · 1 answers · asked by Jay 1 in Physics

If I put this compond into a solution (aq) how would I know that the Fe ions are not bonded to each other? What tells me this information? when Fe disassociates from (SO4)3 why can the ionic form for Fe be written as F2^+3 instead of 2Fe^+3?

2007-09-29 14:00:26 · 1 answers · asked by Gideon 1 in Chemistry

a. An open system exchanges both energy and matter with its surroundings.
b. The collection of matter under study is called the system.
c. Thermodynamics is the study of energy transformations that occur in a collection of matter.
d. A single cell or the planet Earth could be a thermodynamic system.
e. An automobile engine is an example of a closed system.

2007-09-29 13:55:38 · 3 answers · asked by Anonymous in Biology

2007-09-29 13:53:50 · 5 answers · asked by janvincent21 1 in Mathematics

A chain hoist furnished with 120 hp lifts to a height of 40 ft in 20 sec.

2007-09-29 13:50:37 · 2 answers · asked by Jay 1 in Physics

How to get a differential gain > 40V/V with a diferential pair with PMOS input stage and resistive loads with Vdd=2.5V, Vss=-2.5V and Vo=0V by changing any value of bias current, transistor size and resistance?

Differential Amplifier with Resistive Loads

* Set options
.option post probe

* Element Statements
vdd vdd 0 2.5
vss vss 0 -2.5
m1 vout- vin+ 1 vss cmosn w=100u l=1.0u
m2 vout+ vin- 1 vss cmosn w=100u l=1.0u
r1 vdd vout- 50k
r2 vdd vout+ 50k
i1 1 vss 100u
e1 vin+ 2 3 vss 0.5
e2 vin- 2 3 vss -0.5
vcm 2 vss 2.5
vs 3 vss dc=0

* Control statements
.dc vs -0.5 0.5 0.01
.probe v(vout+,vout-)
.tf v(vout+,vout-) vs
.op

* Include device model with filename "cmos05.mod"
.include cmos05.mod

.end

2007-09-29 13:50:18 · 1 answers · asked by Earthman 2 in Engineering

2007-09-29 13:49:30 · 3 answers · asked by janvincent21 1 in Engineering

and how come the sun does not burn our eyes when we look at it when it is red? And, if Superman gets weak under a red sun, how come he doesn't lose his powers when our sun is red?

Questions asked by my grandson, who loves Superman. (He has read all my comics form the 60's, where he learned Superman came from a red sun. OK You nit pickers, yes, I know Superman is NOT real, but, please humor my grandson)

2007-09-29 13:46:34 · 6 answers · asked by Anonymous in Astronomy & Space

let f(x)=Ax + (B/x^2) where A and B are constants. Find values for A and B so that the line y=2x+1 is tangent to y=f(x) when x=-1.

I have no idea how to do this./

2007-09-29 13:42:43 · 1 answers · asked by Mr. Vill 1 in Mathematics

Suppose you're at earth. What looks bigger? Venus or The Moon?

2007-09-29 13:41:19 · 12 answers · asked by lunk_funk 4 in Astronomy & Space

does anyone know the texture,3 practical uses in our every day life and special properties of Galena?please help me ny report is do Wensday!!!!!!

2007-09-29 13:38:56 · 5 answers · asked by penny p 2 in Earth Sciences & Geology

Parallel to 2x+2y=8 and through (-1,-4)

2007-09-29 13:38:08 · 18 answers · asked by TAZ 1 in Mathematics

I'm doing a practice exam for our first Calc 1 test, and question 7 part b) asks: Find f'(x) of y=(x^5 + 4x^3 - x)^6. I know the formula for f'(x) is lim(h->0) [f(x+h)-f(x)]/h, and I can do this problem the traditional way but it would take FOREVER to take all of those x+h's to the different powers, then find the entire f(x+h) to the sixth power and f(x) to the sixth...

Given that this is just a part of one question.. and part a) was easy.. and the test has to be completed within an hour, there must be some exponential rules that allow this to be done much more quickly. Can anyone help?

2007-09-29 13:36:57 · 4 answers · asked by tcotier 1 in Physics

What are the domain of these functions?

f(x) = 4x^4/3

g(x) = (2x^1/3)/3

h(x) = 6x^7/6

2007-09-29 13:36:17 · 2 answers · asked by Asa 1 in Mathematics

2007-09-29 13:35:36 · 11 answers · asked by janvincent21 1 in Mathematics

I'm doing a practice exam for our first Calc 1 test, and question 7 part b) asks: Find f'(x) of y=(x^5 + 4x^3 - x)^6. I know the formula for f'(x) is lim(h->0) [f(x+h)-f(x)]/h, and I can do this problem the traditional way but it would take FOREVER to take all of those x+h's to the different powers, then find the entire f(x+h) to the sixth power and f(x) to the sixth...

Given that this is just a part of one question.. and part a) was easy.. and the test has to be completed within an hour, there must be some exponential rules that allow this to be done much more quickly. Can anyone help?

2007-09-29 13:35:18 · 3 answers · asked by tcotier 1 in Mathematics

two parallel plates 1.0 cm apart are equally and oppositely charged. An electron is released from rest at the surface of the negative plate and simultaneously a proton is released from rest at the surface of the positive plate. How far from the negative plate is the point at which the electron and proton pass each other?

2007-09-29 13:35:02 · 4 answers · asked by biscuits 2 in Physics

2007-09-29 13:33:47 · 1 answers · asked by Anonymous in Biology

Even if I use more zeros, so that 6 9/16 equals 6.5625 and then convert, I end up with, 6 45/8. Can this just not be done so that it will convert back out as 6 9/16 or I am just doing something wrong? Thanks.

2007-09-29 13:30:59 · 4 answers · asked by passmyged 1 in Mathematics

The earth's atmosphere is app. 78 % nitrogen gas and 21%oxygen gas. What do you think will happen if this ratio of N2 to O2 were reversed?

2007-09-29 13:30:08 · 3 answers · asked by angelacute_girl 1 in Chemistry

I know what "car" is, but a Parrot can only know what "this" car is. I can think about "personhood" apart from any particular person, but a Gorilla can't really think about "Gorillahood"--it can only know other Gorillas it sees.

2007-09-29 13:28:14 · 9 answers · asked by delsydebothom 4 in Zoology

2007-09-29 13:26:59 · 4 answers · asked by Anonymous in Astronomy & Space

2007-09-29 13:23:25 · 1 answers · asked by physics 1 in Mathematics

I need info that is accurate, recent, and comprehensive. It would be nice if I could get a daily chart showing temperature, precipitation, and other info for the past two weeks. It can't just all disappear, all the recorded data has to go somewhere!

2007-09-29 13:21:39 · 3 answers · asked by writetome23 1 in Weather

An oxide of nitrogen contains 30.45 mass % N.
(a) What is the empirical formula of the oxide?

(b) If the molar mass is 90 +/- 5 g/mol, what is the molecular formula?

Calculate the number of lithium ions in 1.25 g lithium sulfate.

Thank you

2007-09-29 13:21:31 · 1 answers · asked by Anonymous in Chemistry

I'm so stuck please help me!
Even if you can just do one question it will help!
Differentiate the following:
1) ln(1/x)
2) sin4x^3
3) cos^2(x^3)
4) tan^2(xe^x)
5) ln(sin^3(x^4))

6) If x and y lie on the ellipse x^2/a^2 + y^2/b^2 = 1, show that the slope at any point is given by dy/dx = -(b/a)^2(x/y)

Thank you if anyone helps me! :) x

2007-09-29 13:19:03 · 4 answers · asked by Hayley* 3 in Mathematics

i need a college with a most popular major as pre-med, chemistry or biology or any combo PLEASE HELP ME

2007-09-29 13:16:06 · 6 answers · asked by Anonymous in Medicine