Straipsnis apie gravitacinį lauką ir gravitacinio lauko stiprumą
Kai stumiate knygą ant stalo paviršiaus, kol ji pajuda, jūsų ranka paliečia knygą. Panašiai, kai pririšate daiktą virve ir traukiate jį, kol jis pajuda, jūsų ranka paliečia virvę, o virvė – daiktą. Šiuo atveju virvės stūmimo, traukimo, įtempimo ir panašios jėgos vadinamos prisilietimo jėgomis. Žemės gravitacinė jėga, traukianti link Žemės paviršiaus krintantį vaisių. Arba Žemės gravitacinė jėga, traukianti Mėnulį į Žemės orbitą, atsiranda be Žemės ir vaisiaus bei Mėnulio sąlyčio.
Todėl gravitacinės jėgos arba panašios jėgos vadinamos neliečiamosiomis jėgomis. Kaip vaisius galėtų nukristi, o mėnulis – „kristi“ link Žemės, nesiliesdami tarp Žemės, vaisiaus ir mėnulio? Mokslininkai, įskaitant Niutonas, sunku įsivaizduoti neliečiamosios jėgos sąvoką. Siekiant lengviau įsivaizduoti ir suprasti neliečiamosios jėgos sąvoką, iškeliama lauko sąvoka.
Gravitacinis laukas
When an object with mass is in space, the object produces a gravitational field. The gravitational field of an object with mass m is illustrated in the form of field lines, as shown in the figure below.
The farther from the surface of the object, the distance between the lines of the gravitational field is farther away. Instead, the closer to the surface of the object, the distance between the field lines is getting closer. The closer, the greater the gravitational field strength. The farther, the gravitational field becomes smaller. Likewise, the greater the mass of objects, the more and closer the gravitational field lines. If a test particle is placed near an object that produces a gravitational field, the test particle will experience a gravitational force. The direction of the gravitational force toward the center of the object produces a gravitational field.
The farther from the surface of the object, the distance between the lines of the gravitational field is farther away. Instead, the closer to the surface of the object, the distance between the field lines is getting closer. The closer, the greater the gravitational field strength. The farther, the gravitational field becomes smaller. Likewise, the greater the mass of an object, the more and closer the gravitational field lines.
If a test particle is placed near an object that produces a gravitational field, the test particle will experience a gravitational force. The direction of the gravitational force toward the center of the object produces a gravitational field.
The gravitational field strength
The strength of the earth’s gravitational field experienced by an object above the earth’s surface:
g = gravitational field strength
Fg = force of gravity
mB = mass of earth
RB = radius of earth = 6.37 x 106 m
h = height of objects above the earth’s surface
If we want to calculate the gravitational field strength of a planet, the mass, and radius of the earth (mB ir RB) are replaced by the mass and radius of the moon or the mass and radius of a particular planet.
If we look at the free-fall motion of an object above the surface of the earth, then it is seen as the gravitational acceleration of the earth which is experienced by the object, which is 9.8 m/s2. If the object is still above the earth’s surface (objects do not fall freely), then g is seen as the earth’s gravitational field strength experienced by the object, which is 9.8 N/kg.
