| Even the planets are subject to
Newton's laws of motion, and their circular orbits can also be characterized by the
equations for uniform circular motion. However, the force acting here is special;
where does this mysterious force of gravity which keeps the planets in their order come
from? There are no obvious or visible pushes or pulls like most forces. The
short answer is Newton's law of universal gravitation. Which
applies no only to planets, but to all objects: |
| F = Gm1m2/r2 |
G = universal constant = 6.67 X 10-11
Nm2/kg2 |
| m1, m2 = masses
of particles or objects (kg) |
| r = distance between their centers (m) |
|
From Newton's second law (F = ma), we know that a body of mass
m is proportional to the force. And the force of gravity acting between two bodies
should be inversely proportional to the distance between their centers. G, here, has
the units of Nm2/kg2, and the force is properly in Newtons.
the numerical value of this Universal Gravitational Constant has to be
determined experimentally.The above equation
suggest to the following:
Every particle is attracted to every other particle by a force that,
i) is proportional to their masses
ii) is inversely proportional to the square of the distance between them
iii) acts in a straight line between them |
|
