G Fields Flashcards
what is a field
it is a region where a body experiences a non contact force
similarity and difference between gravitational and electrostatic forces
S:both have inverse square laws with concepts such as potential, field lines and equipotential in common
C:masses always attract but charges can repel or attract
what is newtons law of gravitation
The gravitational attraction force between any two point object is:
-proportional to the product of two masses
-inversely proportional to the distance between their centres squared
gravitational field
region in which an object with mass experience a non-contact force
gravitational field strength
force per unit mass at that point in the field
gravitational potential
work done in bringing an unit mass from infinity to a given point in the field
gravitational potential energy
work done in moving a mass from in infinity to a point in the field
gravitational potential difference
the difference in work done on moving an unit mass between two given points
what is “zero value at infinity”
at an infinite distance the potential is zero
significance of the negative sign on gravitational potential equation
zero potential at infinity so work needs to be done in order to move the object away from the centre
equipotential surface
joined points of equal potential so no work is done when moving along the surface
how to derive T^2@r^3
mv^2/r=GMm/r^2, v=2(pi)r/T
is gravitational potential a scalar quantity
yes
is gravitational field strength scalar
no
define escape velocity
the minimum speed required for an unpowered object to leave the gravitational field of the planet
formula of escape velocity
Ek=0.5mv^2, Ek=GMm/r leads to v=root(2GM/r)
how does the period for the two satellites differ
geo-satellite has the same period as earth’s rotational period whereas the low-orbiting ones is few hours
compare the height for the two satellites
geo=high, low-orbiting=low
compare the speed of two satellites
geo=low, low-orbiting= high
compare the movement of the two satellites
geo=always orbit the same point about the earths surface and remain directly above the equator, low= covering the whole earth
applications of both satellites
geo= tv radio–>telecommunication low= weather observation, environmental monitoring
compare the aerials for both satellites
geo= transmitting and receiving aerials can be fixed
low-polar orbiting= need a tracking facility
define synchronous orbit
when an orbiting body orbits at the same time period with the body being orbited and same direction of rotation as that body
