Science & Mathematics - 21 October 2007

Okay, in my physics class we are working on launching projectiles at an angle. I'm doing a lab that involves launching an object at different angles, but maintaing the same launch spped. I've discovered that the angle that gives the greatest range is 45 degrees, but I don't understand why it is that way.

Also, changing the launch speed but not the angle produces a graph that slants upward. So the mathmatical relationship should be linear, correct??

2007-10-21 13:17:53 · 3 answers · asked by Anonymous in Physics

A roller coaster car of mass 1500 kg starts a distance H = 23 m above the bottom of a loop 15 m in diameter. Friction is negligible.

a) Find the speed of the coaster when it is upside down at the top of the loop.

b) Find the downward force of the rails on the car when it is upside down at the top of the loop.

2007-10-21 13:16:46 · 1 answers · asked by Anonymous in Physics

2007-10-21 13:15:51 · 4 answers · asked by Anonymous in Mathematics

There was a gal who had had a couple of accidents, so her grandma gives her a large sum of money to buy a brand new Volvo. The only condition is that when she gets the car, grandma wants to see it to make sure she didn't buy that Firebird. She drives to grandma's house which is 120 miles away. Assume that she lives right on the highway, and so does grandma -- there's no time lost accelerating(you know)
Because she's not eager to get there, she sets the cruise control for 40 mph and drives the 120 miles to grandma's house. She doesn't want to spend too much time with grandma; so she shows grandma the car and leaves. On the way back she sets the cruise control for 60 mph. same road, same 120 miles, and when she gets home she thinks,"I drove 120 miles up with 40 mph and 120 miles down with 60 mph thats 240 miles, my average speed was 50 mph, so it should have taken me 4.8 hours,right? That's 240 divided by 50 (average speed) comes out to 4.8. But it took 5 hours. How can that be??

2007-10-21 13:14:33 · 5 answers · asked by tuazeee 2 in Physics

Find the intervals on which f increases and the intervals on which f decreases:

(a). f(x) = x (x + 1) (x + 2)

(b). f(x) = x / (1 + x^2)

(c). f(x) = x + sin x, 0<=x<=2pi

Explain your work. Thanks! :)

2007-10-21 13:13:28 · 1 answers · asked by Anonymous in Mathematics

Vector V1 is 7.44 units long and points along the -x axis. Vector V2 is 4.39 units long and points at +55.0° to the +x axis.
I've figured:
V1x= -7.44
V1y= 0
V2x= 2.518
V2y= 3.596

magnitude= 6.0957

but i can't figure what the direction = ?° (counterclockwise from the +x axis is positive)

2007-10-21 13:12:49 · 1 answers · asked by hahahahahaha 1 in Physics

The exact question which I'm having trouble with:

What is the acceleration due to gravity at a distance of 2 Earth radii above Earth's surface?

I have, no idea what this thing is asking. Isn't a radius a distance between the center of an object and its outer shell? So is this thing asking me the pull of gravity on an object, by earth, if the object is twice the distance from earth's surface than the surface and the core? What is the equation for that?

2007-10-21 13:11:48 · 2 answers · asked by paladin_hammer 1 in Physics

....What will be [A] after 1.50 h?

2007-10-21 13:10:04 · 2 answers · asked by Ciso101 2 in Chemistry

i cant seem to find decent information - and it's a topic that would explain a lot about reality to me.
pacemakers do not REPLACE hearts, but make them beat.
artifical hearts - i cannot find reference to the absolute replacement (ie; taking physical real heart away).
if you can find such reference - i need NAMES, and if possible where they can be found. ANY help is appreciated

2007-10-21 13:09:45 · 4 answers · asked by bandaidsrcool 2 in Medicine

I know suicide is stupid..
Why does it matter if we work or live on the street.
Why cant we do drugs if we will cease to exist

2007-10-21 13:09:18 · 12 answers · asked by Anonymous in Biology

calculate the derivative of :

i) sin^(-1) squareroot of (1-x)

ii) tan^(-1) squareroot of (x^2 -1)

iii) (x^2 -1)^(1/x)

2007-10-21 13:06:21 · 1 answers · asked by Talal B 1 in Mathematics

im failing so if you help i will be so happy.

its y and x axis tables.

x = 2 -1 0 -2 1/2 ___ ___
y = -4 2 0 ___ ___ 6 3

2007-10-21 13:02:03 · 4 answers · asked by Anonymous in Mathematics

2007-10-21 13:01:30 · 6 answers · asked by Deenie 6 in Paranormal Phenomena

It could be a spirit or ghost, but I'm having trouble buying he is really a living creature.

2007-10-21 13:01:27 · 8 answers · asked by Anonymous in Biology

In about 20-50 years? Why are they so rare?

2007-10-21 13:00:23 · 9 answers · asked by Dnndsnddbusdbdbdb 2 in Botany

I am a student at a high school that uses the Integrated Mathematics Program. I really would like to see actual statistics that show IMP is a better way of learning math than traditional math lessons. I really do not feel that I have learned much and there is no possible way to study out of the textbook. I consider the textbook to be a book full of questions rather an actual learning tool because there are no lessons in the actual book. The only information given about how to solve the problem is given by the teacher and it usually is brief and what is I believe, not much use in real life, unless if I were to figure out the probability of events or finding out how to put a certain problem in summation notation. Most of the students I know do not like IMP and were so glad they had traditional math problems on our PSAT, rather than all word problems. Please show me official statistics that show IMP is a better way to learn IMP, and your own personal opinions.

2007-10-21 13:00:07 · 3 answers · asked by Steve Y 2 in Mathematics

Scientist can determine the age of ancient objects by a method called radiocarbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope of carbon, 14C, with a half-life of about 5730 years. Vegetation absorbs carbon dioxide through the atmosphere and animal life assimilates 14C through food chains. When a plant or animal dies, it stops replacing its carbon and the amount of 14C begins to decrease through radioactive decay. Therefore, the level of radioactivity must also decay exponentially. A parchment fragment was discovered that had about 78% as much 14C radioactivity as does plant material on Earth today. Estimate the age of the parchment.

No idea where to start on this one?

2007-10-21 12:59:27 · 5 answers · asked by m_carl 1 in Mathematics

5.0 g of NaNO3 is dissloved into 50.0 g of H2O. The intiatil temperature of the water was 21 degrees and the final temperature of the water is 15.7 degrees.

Write the net ionic equation when NaNO3 dissolves in water.

2007-10-21 12:57:21 · 2 answers · asked by Jamie 3 in Chemistry

i need to know for Physical science why is clouds white??

2007-10-21 12:54:02 · 4 answers · asked by Miranda 1 in Weather

The problem is "The height (y) of Marla's model rocket can be represented by the equation y = -16x^2 + 70x + 37 where(x) represents the time in seconds since the rocket was launched, and height is expressed in feet. What was the maximum height of Marla's rocket to the nearest tenth of a foot?" I've got a lot of questions like that one and I have no idea how to answer them. Please help.

2007-10-21 12:52:17 · 3 answers · asked by Anonymous in Mathematics

we went hiking thru some trails and we found this old chunk of something that looks like granite. it has half a word on it. it says KANA .D how would i find out what it is? the park used to be an old military camp and i want to know if it came from there.

2007-10-21 12:50:50 · 2 answers · asked by jana p 1 in Earth Sciences & Geology

Josh and Mike live 13 miles apart. Yesterday Josh started to ride his bike towards mikes house. a little later mike started to ride his bike toward joshs house. when they met josh had ridden for twice the time as mike and at 4/5 mikes rate. How many miles had mike ridden when they met?

2007-10-21 12:50:26 · 1 answers · asked by ~USA~ 2 in Mathematics

2007-10-21 12:50:23 · 1 answers · asked by Anonymous in Mathematics

2007-10-21 12:49:45 · 4 answers · asked by Anonymous in Physics

(only using differentiation)
1) how fast is distance changing after 1/2hr (ans. 500mph)
2) how fast is distance between object and radar changing when object passes directly above the radar. (ans. 0)
3) suppose that line through the radar and object make an angle Θ with horizontal. how fast is Θ changing 10min after object passes over radar. (need help with this one)

give hints and ans for 3 part

2007-10-21 12:47:15 · 3 answers · asked by Anonymous in Engineering

how do you find the coordinates of the foci of an ellipse?

also

how do you write the equation of an ellipse

and parabola?

2007-10-21 12:40:49 · 1 answers · asked by nativebeauty22 1 in Mathematics

2007-10-21 12:38:20 · 2 answers · asked by mina 1 in Zoology

I'm beginning to study biology and I've been looking under microscopes and all that. I don't understand why a cell is alive..what's keeping it alive? How does it know what to do..like a mini factory..with the components working together? It seems like it has some sort of intelligence that directs it. What is keeping the cell alive?

2007-10-21 12:32:44 · 5 answers · asked by Anonymous in Other - Science

i know how to find it..justu that i am not getting the right answer!!!!!

2007-10-21 12:31:24 · 2 answers · asked by Riya A 1 in Mathematics

2007-10-21 12:29:38 · 3 answers · asked by ♥ Lisa ♥ 2 in Earth Sciences & Geology