Physics - July 2007

I was just reading on wikipedia about radiation poisoning.(very interesting i recommend a gander at it) Anyway it lists different levels of exposure and survivial rates and i was wondering that if say you got exposed to 100Sv or something very high to a small area like say your finger would that kill you? Also where is the line drawn between maximum amount of area exposed and death.

2007-07-15 10:44:55 · 10 answers · asked by Anonymous

I've seen 150mW lasers that cut through electric tape and ignite wood from 20metres away, but then I see 240mW lasers that couldn't turn petrol-soaked paper into flame. Am I missing something here?

2007-07-15 10:24:12 · 9 answers · asked by Anonymous

2007-07-15 09:43:01 · 4 answers · asked by JAMES 4

2007-07-15 08:46:46 · 3 answers · asked by Anonymous

A biker is riding at a steady vr=2.1km/hr. When the biker is L=8.8km. from the finish line. A bird then begins flying from the biker to the finish line at vb=6.3km/hr. When the bird reaches the finish line, it turns around and flies back to the biker. We will assume that the bird occupies only one point in space. So the bird has no length.How far does the bird travel.

2007-07-15 08:41:46 · 4 answers · asked by ... :) 2

If she were to jump off the stool, while falling, the reading on the spring scale would read:
1. greater than 1 N
2. 1 N
3. less than 1 N
Explain your answer:

2007-07-15 08:10:58 · 2 answers · asked by Anonymous

If you were able to go to the top of a tall building and simultaneously drop an apple and a basketball, they would both hit the gound at about the same instant because
a. the force of gravity on them is equal.
b. they have the same mass.
c. air resistance on both is the same.
d. they have the same amount of kinetic energy.

2007-07-15 08:08:47 · 7 answers · asked by Anonymous

When a car accelerates from a standing start, a person appears to be pressed backward into the seat cushions. Which of the following best explains why this happens?
a. The person gets lighter as the car accelerates.
b. The car is moving forward faster than the person.
c. There is no reaction to the force of the car taking off.
d. Gravity is pulling the person in the direction the car is moving

2007-07-15 08:06:55 · 3 answers · asked by Anonymous

ok, so we're all familiar with the theoretical temperature of absolute zero.

at −459.67°F there is a complete absence of movement among particles.

taking this concept into the quantum world becomes a very interesting thing to ponder. if there is no kinetic energy at the sub atomic level wouldn't the science of quantum probability fall apart, thereby actually erasing matter?

i don't know, think about it

2007-07-15 08:02:50 · 4 answers · asked by marcin p 1

Suppose you would live in a two-dimensional world, a Flatland, like along a sheet of paper, having no experience of a third space dimension, just like we have no experience of a fourth space dimension. Then you would sometimes get completely unexpected visits from the third space dimension, like for example when somebody writes on the paper, tears or cuts it into pieces or puts it to fire. You would never see the danger coming, as your sight works only along the sheet. Still, you might lose a loved one because he or she was some inches away from you when the paper was cut. Physicists say there are more than three space dimensions. If that is true, how come we are not similarly surprisingly torn apart by objects, maybe some equivalent of asteroids or other stuff, that move in the fourth and higher space dimensions, thus unabling us to ever see the danger coming before it's already here? Is there no matter moving in the fourth and higher space dimensions, or what is the explanation?

2007-07-15 07:14:12 · 5 answers · asked by Justin Case 1

How about this one?

Q: A girl drops a coin from the roof top to the ground 6 meters below. If the coin is released from rest, how long is it in the air?

t = ?
h = 6 meters

2007-07-15 07:04:03 · 4 answers · asked by mikko 1

if an object is fired at a vertical angle (90degrees) from horizon, at a heighth of 156.25', what was the initial velocity.

2007-07-15 07:02:07 · 2 answers · asked by ftm821 2

Time goes only forward, not backwards. But in space, you can move back and forth, left and right, up and down. For each space dimension, you can go in two directions. If time would work in the same way, it would be possible to travel backwards in time. But how would it be the other way around: what would it be like if in all the three space dimensions there were only one direction, like with time?

2007-07-15 06:49:14 · 7 answers · asked by Justin Case 1

...because string theory doesn't seem to be.

2007-07-15 06:22:54 · 6 answers · asked by mesun1408 6

Q: A penny is dropped from rest from the top of the building. Considering the height of the building is 427 meters & ignoring air resistance, find the speed with which the penny strikes the ground.

-I need help for my physics exam, any help would be greatly appreciated.

2007-07-15 06:21:20 · 7 answers · asked by mikko 1

I'm trying to find the rms values of E (electric field) and B (manetic field). I'm only given power and the diameter of the laser beam. I'm not sure where to start with the problem.

2007-07-15 06:10:02 · 2 answers · asked by babykrisbach1 2

and why does it behave like it does

2007-07-15 06:06:22 · 6 answers · asked by Anonymous

I am going to start univeristy in September 2008, and am hoping to study Physics. The summer holidays are approaching and I as wondering whether anyone can recommend any Physics books which I could read over the break? I have only done my AS so far, so if you know of any books I won't find hard to understand, please tell me!

2007-07-15 06:03:45 · 5 answers · asked by lykastar 3

If a ball on a string suddenly becomes twice as heavy, the force on the string necessary to maintain the same velocity will be
a) twice as great
b) four times as great
c) one-half as much
d) one-fourth as much
e) none of the above

2007-07-15 05:46:28 · 3 answers · asked by regina l 1

The last option suggests that at a fundamental level there is no distinction between real concrete stuff and abstraction. Here is my point. Einstein General Relativity says that spacetime is more like real stuff, because it follows its own equation. Non uniform motion (for example of a spinning object) must exist in relation to spacetime, some real stuff. Yet, it is conceptually very difficult to consider that spacetime in itself is real stuff. Usually, we think that the stuff that progresses in time is what is real, whereas past and future and even time itself are concepts. In other words, we think of spacetime as an abstraction that is required to express the relationships between events. Are these two views inconsistent? Maybe not. After all, through physics we tried to find the "real concrete stuff" out there and we found that it is an abstraction only created when we observe. So, why not considering that the intelligent laws, abstraction, spacetime, etc, is what is real?

2007-07-15 04:51:24 · 2 answers · asked by My account has been compromised 2

what is the orbital velocity of an object 4.431844x10^-03 m from the surface of a "earth mass" blackhole.

2007-07-15 04:28:42 · 3 answers · asked by ftm821 2

2007-07-15 04:11:19 · 11 answers · asked by Anonymous

dear users
subject:magic fountain-dancing color and water with coordination of variose special musical note as(do re mi ...) . our question is to find equivalent frequncy of light against frequency of music sound in scientific detail. magic fountain dancing coclor and water special relative music (do re mi fa ...) will give a very nice , enjoyable and energetic feeling like meditation moode.

2007-07-15 03:56:45 · 3 answers · asked by Anonymous

and if ur not in science u might not answer

this is the third time I'm posting this quiz

for what time does static charge flow?

for milli to pico seconds...right?

Now tell me if i am thinking right-

More the surface area of a plate more will the time taken for it to flow.

Also time is inversely promotional to potential difference....right??

any other factors?

do we have a formula to compute the time?

2007-07-15 03:39:44 · 5 answers · asked by Anonymous

Kindly give your answer based on the physics behind it.

2007-07-15 03:35:13 · 2 answers · asked by Abhay Kumar 1

if we were to compare the distance covered by an ant to the distance covered by an average 6 foot man, how fast would an ant be traveling if it were scaled up to human size? I have watched them at work and they can cover some distance in a very short time!

2007-07-15 03:27:34 · 4 answers · asked by coffeeluvr 1

2007-07-15 03:05:59 · 17 answers · asked by satar032 2

2007-07-15 02:51:58 · 7 answers · asked by genesis 1

2007-07-15 02:50:35 · 3 answers · asked by morrobless 1

I have a prescription to make a power lens.

What will be the best possible equation to find the Total Power Lens according to the prescription.

2007-07-15 02:32:01 · 1 answers · asked by Rizwan 1