metode i znacaj odredjivanja gravitacione konstante 19

							    seminarski rad

   metode i značaj
      određivanja
gravitacione konstante
        “big G”
tri fundamentalne univerzalne
       konstante u prirodi



      brzina svetlosti C
    plankova konstanta h
  gravitaciona konstanta G
             Gundlach said:

"That is a huge embarrassment for modern
  physics, where we think we know
  everything so well and other constants are
  defined to many, many digits.“
“Ovo je velika neprijatnost za modernu
  fiziku, gde mislimo da znamo sve tako
  dobro i gde su druge konstante određene
  sa mnogo, mnogo decimala.”
 isaac newton
     1678



    mM
F G 2
     r
lord henry cavendish
                   henry cavendish
                        1798
                 G=6.75x10-11Nm2/kg2
The torsion balance experiment of Henry Cavendish who in 1797 was the first to experimentally
                            measure the gravitational constant G.
prikaz laboratorijske vežbe
      neki od razloga za pojavu
        sistematskih grešaka
 promenljivost torzionog momenta
 pomeranje podloge (podrhtavanja zemlje)
 uticaj masa tela iz okruženja
 nehomogenost masa tela koja su sastavni
  deo eksperimenta
 gradijent gravitacionog polja
 gradijent temperature
 magnetni i električni uticaj
skica eksperimenta torzionom vagom
r  r0 sin t   
                           mM
F  k                F G 2
       I
                            r
T  2
       k

  k                    kr
                            2
                       G
  F L / 2             mML
               kr       2
            G
               mML
 G gravitaciona konstanta
 L rastojanje između tela malih masa
  ugao otklona
 k torziona konstanta
princip slobodnog pada
 Schematic view of the mass arrangement. The test masses are alternately connected to
the balance by means of the “mass exchanger” and their weight difference is determined.
 The field masses are moved between the two positions I and II. The forces on the upper
test mass due to the Earth, the field masses and tidal forces are plotted for the two field-
                    mass positions on the left and right of the figure.
The orbiting Lageos satellite monitors its position relative to the Earth using reflected laser
light. From the measured gravitational force between satellite and our planet, and

independently measuring G, one can calculate the mass of the Earth.
fabry-perot eksperiment
The apparatus used by the research group at the University of Washington, Seattle, to measure G to
record high precision. The device, about two feet across, measures the attractiveness between a

hanging plate (hidden inside the cylinder) and several spheres which rotate about the cylinder.
tačnost sata je uslovljena konstantnom vrednošću perioda oscilovanja torzionog klatna za
                                  dati momenat inercije