physics in space

PHYSICS IN

SPACEAnghel Theodor

Ghiban Vlad

ThV Team National College, Iasi, Romania


Law of Gravity


“Every particle in the Universe atracts every other particle with a force directly proportional with the product of the particles’ mass and inversely proportional with the square of the distance between them”

This law was enounced by Isaac Newton, after the well-known experience with the apple.


m1m2

r2Fg=k

m1

m2

→ F1

→F2

r

k = 6,673 x 10-11 N·m2·kg-2


Starting from this ecuation and customizing for Terra, we obtain the force The Earth attracts us with, our weight (“g force”).

G=kr2

mp·m

, where mp is The Earth’s mass, 5,975 x 1024 kg, and m is our mass.


This way we can define the gravitational field, a vector field which descrebes the gravitational force that actions on an object in every place in space, on mass unity.


Γ=kmr2

For The Earth, this field is the gravitational acceleration (g, at The Earth’s surface!!!), equal to approximate 9,8 N/m2, so G = m·g

Fg=Γ·m


If we imagine a trip from The Earth’s centre to space, having the posibility to measure the gravitational field in every point we are….

…we will observe that it will vary like in this diagram:

Kepler’s Laws


http://imagine.gsfc.nasa.gov/docs/features/movies/kepler.html


The german astronomer Johannes Kepler enounced a series of 3 laws that contradicted all the beliefs referred to the trajectory of a planet around a star.


First Law:

“The orbit of every planet is an ellipse with the Sun at one of the two foci”


Second Law:

“A line joining a planet and the Sun sweeps out equal areas during equal intervals of time”

It results that the velocity of the platen increases as it’s closer to the Sun.


Third Law:

“The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.”


Special Relativity Theory

-Twin’s paradox-

http://ro.wikipedia.org/wiki/Teoria_relativit%C4%83%C8%9Bii_restr%C3%A2nse

http://ro.wikipedia.org/wiki/Paradoxul_gemenilor


The famous scientist Albert Einstein enounced, in 1905, the theory that proved to be the physics’ most important theory, the one that links two dimensions that seemed to have nothing in common, THE SPACE and THE TIME.


“It’s impossible to accelerate a corpus to the speed of light”

“the speed of light in vacuum, c=2,9979·108 m·s-1, is constant,

not depending on the observatory’s state of motion”

“The time and the space are perceived different, the measurements of length and time are depending to the observatory’s state of motion”


Therefore, using Lorentz’s parameter, Einstein linked the state of motion and the time, starting the famous “Twin’s paradox”

ς=1

1-v2/c2


Considering two twins, X and Y. X goes into a space travel, with the velocity v=0.86 c, 86% of the speed of light, while his brother, Y, stays in repose on the Earth.

Let X travel a distance of 4,45 light-years, so the time of the trip to be 10,28 years…


…so, Y will be older with 10,28 years. But, according to the relativity theory, X will be older with just 5,14 years.

Δt’ = Δt ·ς = Δt · (1-v2/c2)1/2

= 10.28 · (1-0,73)1/2

= 10.28 · 1/2 = 5.14 years


Even if both brothers are moving with equal relative velocities, X will “age” less, his acceleration to get to the “slow down of time”


We can go on and verify every law of physics in space, but the result will be always the same: îin the whole UNIVERSE, the laws of physics are valid and they describe every phenomena.

So, even if we consider Albert Einstein’s deliverance, under which “God is not playing dices”, or the one of Stephen Hawking, “God is a physics law”, the conclusion is that PHYSICS is everywhere.

physics in space

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