Science & Mathematics - 11 September 2007

2007-09-11 18:21:13 · 4 answers · asked by Larry 3 in Earth Sciences & Geology

i dont no if the sky is blue or not?

2007-09-11 18:13:17 · 14 answers · asked by arash m 1 in Earth Sciences & Geology

Traumatic brain injury such as concussion results when the head undergoes a very large acceleration?
Generally, an acceleration less than 800 m/s2 lasting for any length of time will not cause injury, whereas an acceleration greater than 1000 m/s2 lasting for at least 1 ms will cause injury. Suppose a small child rolls off a bed that is 0.44 m above the floor. If the floor is hardwood, the child's head is brought to rest in approximately 1.9 mm. If the floor is carpeted, this stopping distance is increased to about 1.2 cm. Calculate the magnitude and duration of the deceleration in both cases, to determine the risk of injury. Assume that the child remains horizontal during the fall to the floor. Note that a more complicated fall could result in a head velocity greater or less than the speed you calculate

hardwood floor magnitude______ m/s2 duration ______ ms

Carpeted floor magnitude_______m/s2 duration ______ ms


so far i got...I need to know how to get hardwood and Carpeted floor magnitude


First, calculate the speed of the infant just before impact:

d=.5*g*t^2
t=sqrt(2*.44/9.81)
=.3 sec

speed = g*t
=9.81*.3
=2.94 m/s

Hardwood

Deceleration distance
d=.5*a*t^2
.0019 =.5*a*t^2
a=.0038/t^2
Average speed
v=.5*a*t
=.5*2.94
=1.47
a=2.94/t

Using the equations together
2.94/t=.0038/t^2
t=.0038/2.94
=1.3 ms
a=_____ m/s^2

Hardwood bad

Carpet

The average speed is still the same
a=2.94/t

the deceleration is
a=.0248/t^2

Again solving simultaneously
t=.0248/2.94
=8.4 ms
a=_____ m/s^2

Carpet= no trauma.

Thank you

2007-09-11 17:56:57 · 1 answers · asked by bp 1 in Physics

The cost of an Aardvark personal computer is $40 less than twice the cost of an Afghan computer, while and armadillo computer costs $70 more than an Afghan..
If an order of two Afghans, one Aardvark, and three armadillos totals $ 6820, what is the cost of each type of computer?

Please show ur work.Thank you.

2007-09-11 17:54:20 · 6 answers · asked by Chaz 1 in Mathematics

geog homework

2007-09-11 17:46:26 · 4 answers · asked by fliiipster 2 in Weather

I'm having a real hard time with a Chemistry homework question:

A sample 13.03 g of gas was collected and found to have a volume of 6.742 L at 46.6 degrees Celsius and 723.3 torr. What is the molar mass of the gas?

I converted 723.3 torr to 0.9517 atm, and 46.6 celsius to 319.75 K. I then worked it like this using the PV=nRT equation:
(0.9517 atm)(6.742 L) / (0.0821)(319.75 K) = 0.244 mol
(0.244 mol)(13.03 g/mol) = 3.18 g

However, my program says that 3.18 is not the correct answer. What am I doing wrong?
Any help is greatly appreciated!!

2007-09-11 17:45:51 · 2 answers · asked by jfutch5 1 in Chemistry

2007-09-11 17:45:04 · 8 answers · asked by shriya 2 in Biology

2007-09-11 17:41:34 · 6 answers · asked by Anonymous in Other - Science

The density of a penny is 8.56 g/ml. If the density of copper is 8.96 g/ml, and the density of zinc is 7.14, what percent of the penny is copper? What percent is zinc?

2007-09-11 17:40:39 · 2 answers · asked by lirael1019 1 in Mathematics

2007-09-11 17:39:57 · 9 answers · asked by Adorable B 1 in Weather

He's one of my favorite people ever.

2007-09-11 17:37:28 · 4 answers · asked by Anonymous in Other - Alternative

Vector m has a magnitude of 5 m directed east
Vector p has a magnitude of 4 m directed 35 degrees west of due north.
1)What are the magnitude and direction of vector m + vector n
2)What are the magnitude and direction of vector n - vector m

I don't get how to draw the diagram to set up my problem, what exactly is 35 degrees west of due north? is the angle still going to be 35? (its in the 2nd quadrant isn't it)?
Also how would I find the magnitude and direction...thanks

2007-09-11 17:36:45 · 4 answers · asked by superman 4 in Mathematics

Can some one show me how to solve the equation, 4^x + 4^-x = 5/2, algebraically?
I also need help finding the inverse fuction of sqrt(3-x), which I think is x^2 - 3, with domain restrictions. Any help is appreciated. Thanks.

2007-09-11 17:35:57 · 2 answers · asked by Chomp 2 in Mathematics

2007-09-11 17:29:44 · 12 answers · asked by texan3715 1 in Mathematics

2007-09-11 17:27:39 · 6 answers · asked by ryannnnn 1 in Mathematics

tasty treats finds that its profit from the sale of ice cream increeases by 5% per week during the 15-week summer season, Suppose the profit for the first week is $30. Determine the profit for the season.

2007-09-11 17:23:26 · 4 answers · asked by Anonymous in Mathematics

the measure of an angle is 10 less than 4 times the measure of its complement....find the measure of the angle

2007-09-11 17:22:22 · 6 answers · asked by JOGOO 2 in Mathematics

2007-09-11 17:19:15 · 12 answers · asked by peterkarsai59 1 in Mathematics

2007-09-11 17:18:42 · 3 answers · asked by peterkarsai59 1 in Mathematics

Hey everybody...I'm still stuck on trig sub integrals.

I have integral sqrt (x^2-9)/ x^3 dx

and I've gotten down to

1/3 integral 1 - cos 2 theta .... but I'm stuck after that...
I know that theta is inverse sec (x/3). but I'm clueless of how to end this problem. If possible, please show me the steps of how you proceed through the problem.

Thank you.

2007-09-11 17:18:12 · 1 answers · asked by J.W. 2 in Mathematics

One urn contains 7 white balls and 3 black balls, and a second urn contains 4 white balls and 2 black balls. A ball is selected from each urn, and is placed in a bag containing 5 white and 6 black balls. What is the probability of drawing of drawing a white ball from the bag?

2007-09-11 17:17:58 · 3 answers · asked by sky_blue 1 in Mathematics

1. The average of any two consecutive numbers is an even number.

2. Any four-sided polygon is a square.

3. The square of any integer is a positive integer.

2007-09-11 17:17:56 · 2 answers · asked by Anonymous in Mathematics

the structural backbone of any membranous structure in a cell is the..._______? why?

a.phospholipid bilayer

b.glycolipids

c.membrane bound proteins

d.steroids

e. both b and c are correct

2007-09-11 17:15:28 · 2 answers · asked by Na.La. <3 5 in Botany

2007-09-11 17:14:35 · 6 answers · asked by jubka1 2 in Biology

2007-09-11 17:13:55 · 5 answers · asked by blanca r 1 in Earth Sciences & Geology

2007-09-11 17:12:54 · 1 answers · asked by Peter A Child 1 in Physics

give me several reasons y

2007-09-11 17:07:10 · 4 answers · asked by pkc_wan 1 in Mathematics

plz its really urgent.....no silly answers plz...and plz tell any good website for buying this book
or any good shop in india in delhi.

2007-09-11 17:02:45 · 4 answers · asked by Anonymous in Engineering

Please show work

2007-09-11 17:02:00 · 2 answers · asked by texan3715 1 in Mathematics

Pl. I know that, the Earth rotate from right to left its own axist. Incase if the Earth rotate from left to right on its axist,.... do you think the sun will rise from the west and set on the east???

2007-09-11 16:57:08 · 5 answers · asked by LoCo#33 1 in Astronomy & Space