chapter 7: gfield 🌎 Flashcards
what is the Newton’s Law of Gravitation?
2 point masses attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
what is the formula for gravitational force?
GMm/r^2
definition of gravitational field
a region of space where a mass experiences a force due to the presence of another mass
what are the properties of gfield lines
- indicates direction of force a mass would experience if it were placed at that point in the field
- lines never cross one another
- stronger field have more closely spaced lines
- in uniform field, lines are parallel and equally spaced
definition of gravitational field strength
gravitational force per unit mass acting on a test mass placed at that point
formula for gfield strength
g=GM/r^2
what are the key features of geostationary orbit
- period of orbit is 24h
- orbits west to east
- an orbit directly above the equator
why must the geostationary orbit be above the equator
gravitational force exerted by earth on satellite is towards centre of earth, so any circular orbit of satellite must always have its centre of orbit coinciding with centre of earth
do all geostationary satellites located at the same height above earth surface?
yes
do geostationary satellites have same linear speed?
yes
definition of gravitational potential
work done per unit mass by an external agent in bringing a test mass from infinity to that point without a change in kinetic energy
where is gravitational potential 0?
at infinity
definition of gravitational potential energy
work done by an external agent in bringing the mass from infinity to that point
why is GPE always negative?
since GPE at infinity is taken to be zero and gravitational force is attractive in nature, external force to bring small test mass from infinity to that point acts in opposite direction to the displacement of the small test mass —> work done by external force is -ve
