| 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) |
|
|
| g = Gmearth/r2 |
mearth = mass of earth
= 5.97 X 1024 kg
r = distance from center of earth to object (m) |
|
All around Earth revolve communications satellites, old pieces
of past rocket launches, even garbage which has been discharged by past space missions.
How do these objects remain in their orbits around the planet without falling back
down to earth? High speed, and the force of gravity creates centripetal
acceleration:
|
| Gm1m2/r2
= mv2/r |
r = distance from center of earth to object
m1 = mass of object (kg)
m2 = mass of earth (kg)
v = speed of orbit around earth (m/s) |
|
The above equation can be simplify to:
|
| Kepler's third law: r3/T2 = Gm1/4 2
|
| If we want to calculate how much
work is required to move two objects further away from each other: W =Fd
(as we have learned in work & energy section)
F = Gm1m2/r2
Thus, |
| W = d(Gm1m2/r2) |
r = distance from center of Earth to object
(m)
m1 = mass of object (kg)
m2 = mass of earth (kg)
d = distance two objects are moved apart (m) |
|
|
