How high does the atmosphere go?

We were wanting to look at information that one would need, in order to calculate how long it would take for the NASA UARS satellite to reach the earth's surface once it entered the atmosphere. 

You can read more about satellites here http://www.nasa.gov/audience/forstudents/5-8/features/what-is-a-satellite-58.html

This concept was obviously "theoretically" only and was not be accurate in any way but its was project we decided to look at.

At the end of it we realised that we needed to learn more about the difference between speed, acceleration and velocity.  There were also a couple of other things that we learnt.

At first we thought that if we could get certain info such as mass, speed and distance, we could use one of the physics formulas we had learnt about to work this out.  

We had a look at this website http://www.ucar.edu/learn/1_1_2_2t.htm  How high does the atmosphere go?  It turned out that each of the websites we looked had different measurements but we used the first one as it was only a theory we were looking at.

The info on the website, states that the "thickness" of the atmosphere (the distance between the earth's surface and the "top" of the atmosphere) is not an exact measure. 

On this site they stated that the atmosphere is made up of 2 layers.  The layer that is closest to the earth is the Troposphere (7 miles. The Upper layer of the atmosphere is called the Stratosphere (29 miles).

The approximate measure of the atmosphere is therefore 36 miles. (according to this website).  We used this measurement.  

(There is also info on http://www.enchantedlearning.com/subjects/astronomy/planets/earth/ which states "The Earth's atmosphere is about 300 miles (480 km) thick, but most of the Earth's atmosphere is within 10 miles (16 km) of the Earth's surface.") *but we had used the first info for our theory - no matter.

If we used the formula:  Time = distance / velocity we considered that we could work out, theoretically, how long the satellite would take to reach the surface.  Obviously there are many factors involved, including friction (burn up), gravity, rotation of the earth, path of the satellite etc.

We get the velocity from this website:  

Time = distance / velocity

Time = 36  miles / 18000m/h   

Time = 0.002 hours

To convert this we x by 3600s (1 hour)

Time = 7.2 seconds.

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(Is this the correct way to convert to seconds ? - I think it is)

This is a very short time but it does make some sort of sence, if you consider that when we think we see a falling star, it is actually only a piece of space debris or meteor etc entering the atmosphere.  The time that a falling star takes is seconds as well!

Here is another site that again has different measurements and additional layers to the atmosphere.  http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html.  They list the layers of the atmosphere as Trophoshere , Stratosphere, Ionosphere and Mesosphere = 550km in total.

We also used these measurements in the same formula:

Time = distance / velocity

Time = 550km / 28968.19km per hour (18000m/h)

Time =  0.019 hours

To convert this we x by 3600s (1 hour)

Time = 68 seconds

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After this we looked at the NASA website for info on the atmosphere.  Again it has different info and more layers, going upto 600km.  http://www.nasa.gov/audience/forstudents/9-12/features/912_liftoff_atm.html  This has the most info and presumably it is accurate as they have done a lot of research.

***One interesting thing we did find out BTW is that NASA are crashing this satellite intentionally!  That's something to think about.  We also learnt about orbital debris and how much there is in orbit.

EXTRACT  "Its orbit was been altered by Nasa deliberately to make it crash – but it is now coming down sooner than expected due to changed atmospheric conditions."

Read more: http://www.dailymail.co.uk/sciencetech/article-2040818/Satellite-falling-earth-1-3-200-chance-NASA-UARS-hit-person.html#ixzz1YnL4pVvX

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Next we looked at the formula

Force = mass x acceleration

We know the mass is 6 tonnes and 1 tonnes = 1000 kilograms therefore the satellite is 6000kg. This info of 6 tonnes comes from news reports and the NASA site.  Acceleration is 18000 miles per hour. (Note:  This figure of 18000 miles/hour comes for http://www.dailymail.co.uk/sciencetech/article-2040818/Satellite-falling-earth-1-3-200-chance-NASA-UARS-hit-person.html and other sites) 

So Force = 6000kg x 18000 miles per hour

Force is measured in Newtons (N) therefore

Force = 108 000 000 N ??

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Alternatively if I convert the 18000 miles per hour to km/h, I get  28968.19km per hour.  (I used this to convert miles to km  http://www.calculateme.com/Speed/MilesperHour/ToKilometersperHour.htm)

My calculation for Force would then be = 6000kg x 28968.19km per hour

Force = 173 809 140 N

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In any event both answers are extreme amounts of Force!  

Bear in mind, though that the satellite is set to burn up and break up the final force will differ.  This is theoretical only.  It would also make a difference to the answer in Newtons, if you use km/h or m/h. (As shown).  I think it is correct to use Km/h and not m/h for calculations, however in the UK the unit of measure is m/h so how does this effect Newton calculations.    As I am just learning about these formulas and force/mass/velocity etc - these are all just thoughts and I know I am only learning and can get things wrong.

Its interesting to think about things....

I want to look more at the difference between speed, acceleration and velocity.  They are both measured in m/s and km/h.... - depending on what system your country uses - what unit should you use for calculations??  As it gives different answers!  Also want to look at the difference between weight and mass.

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Read this website to learn how satellites stay in orbit...http://library.thinkquest.org/C007258/Keep_Orbit.htm

It seems they travel a distance and fall closer to the earth during that travelling (like a ball when you throw it).  Because the earth has constant curves the satellite does not actually fall into the earth.  It just has constant movement around the earths curves.  You have to read the article yourself to understand it.

SCIENCE/MATHS: Proportion, gravity and complex formulas

 = is proportional to


This is a good site to explain proportion.

http://www.easymaths.com/getting_things_out_of_proportion.htm

HOW I GOT TO LOOKING AT PROPORTION
You see, I was busy with my science today and the topic was planets.  When I had finished the section and the questions at the end of the section, I decided to do a presentation on planets and learn a bit more than was in the study book.

One of the sites I looked at gave me this to think about:

"gravitational force is proportional to the product of their masses and inversely proportional to the square of the distance between them."

Ok so what does that mean to someone in P7?

....this lead us to look at formulas in general and how they are written and the symbols they use and then the complicated formula of gravity.

Some simple formulas - http://www.math.com/tables/geometry/areas.htm

Interesting....

A forceful recipe to measure gravity

2 measures of different masses
1 x cup of proportionality
1/2 cup of inverse proportionality
1 000 000 light years of distance
375 ml H2O (Water)
1 x pinch of salt

Mix ingrediants in a bowl and stir for 1 minute
Preheat solar system on medium and bake surface for 365 days.

Note your results.

SCIENCE: ISAAC NEWTON

I have compiled some info on Sir Isaac Newton whose theories on gravity are important.

Isaac Newton was born in England, on xmas day in 1642 (the year Galileo died).

During the time he was studying, the plague was spreading across Europe and the university closed.  Newton returned home and spent 2 years concentrating on mathematics and physics problems. 

He later wrote that during this time he first understood:

• the theory of gravitation,
• the theory of optics (he was the first to realize that white light is made up of the colors of the rainbow), and
• a lot of mathematics, i.e. integral / differential calculus and infinite series. 

On returning to Cambridge in 1667, he began to work on alchemy.

Newton’s first major public scientific achievement was the invention, design and construction of a reflecting telescope.  He ground the mirror, built the tube, and even made his own tools for the job.  This was a real advance in telescope technology, and ensured his election to membership in the Royal Society.

Gravitational Force 

The legend is that Newton saw an apple fall in his garden in Lincolnshire, thought of it in terms of an attractive gravitational force towards the earth, and realized the same force might extend as far as the moon.  He was familiar with Galileo’s work on projectiles, and suggested that the moon’s motion in orbit could be understood as a natural extension of that theory. 

Ref:  http://galileoandeinstein.physics.virginia.edu/lectures/newton.html
Ref:  http://www.zephyrus.co.uk/isaacnewton.html
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**Another interesting thing in the article I read is this:

Later in the 1670’s, Newton became very interested in theology.  He studied Hebrew scholarship and ancient and modern theologians at great length, and became convinced that Christianity had departed from the original teachings of Christ.  He felt unable to accept the current beliefs of the Church of England, which was unfortunate because he was required as a Fellow of Trinity College to take holy orders.  Happily, the Church of England was more flexible than Galileo had found the Catholic Church in these matters, and King Charles II issued a royal decree excusing Newton from the necessity of taking holy orders! Actually, to prevent this being a wide precedent, the decree specified that, in perpetuity, the Lucasian professor need not take holy orders.  (The current Lucasian professor is Stephen Hawking.)