Gravity Flashcards
What is the strength of a gravitational field
Force per unit mass on a small test mass placed in that field
What is gpe
The energy of an object due to its position in a gravitational field
Where is the position of 0 gpe
Infinity
What is gravitational potential in terms of gpe
The gpe per unit mass of a small test mass
What is gravitational potential in terms of work done
It is the work done per unit mass to move a small object from infinity to that point
What is change in gpe
dW=mdV
What are equipotentials
Surfaces if constant potential, this means no work needs to be done to move along them
What is the potential gradient
The change in potential per metre
What is the negative of the potential gradient equal to
g
What is the gravitational potential of a spherical planet in terms of G and M
-GM/r
Escape velocity equation
v= root(2gr)
What does newtons law of gravitation assume about the force
It is always attractive
Is proportional to the mass of the objects
Is proportional to 1/r^2
What is keplers third law
T^2/r^3 is a constant for all planets
What are geostationary satellites
Satellites that orbit directly above the equator with a time period T=24h
This means it remains in a fixed position relative to the earths rotation
Total energy of an orbiting satellite
-GMm/2r
Kinetic energy of an orbiting satellite
GMm/2r
Potential energy of an orbiting satellite
-GMm/r
