Paper 2: Gravitational Fields Flashcards
What is a force field?
It is a region in which a body experiences a non-contact force.
When are force fields present?
When there are interactions between masses or charges.
What type of force is gravity?
It is attracive between all matter with mass.
Define Gravitational Field strength
Force per unit mass in a gravitational field. NKg-⁻¹
What are some similarities between electromagnetic and gravitational forces?
- both obeys inverse square laws of intensity
- both have euqapotentials
- can be reprwesented via field lines
What are some differences between gravitational and electromagnetic forces?
Gravitational forces are only attractive whereas electromagnetic forces can repel or attract according to their charges.
What can field lines tell you about a field?
- The direction of the field
- desnity of lines can show the strength
What is g in a radial field?
g is the proportionality constant at that point between the force and mass. where g = GM/r²
define gravitational potential
potential energy per kilogram
JKg⁻¹
What is Gravitational Potential?
potential energy per kg at any point in the field.
What is the work done by moving a mass in a field?
Mass × Δ V
What is the gravitational potential difference?
Gravitational Pd is trhe energy needed to move a unit mass between equipotentials.
Define Gravitational Potential Difference
ΔW =mΔV
What is an euipotential? surface?
A surface in which every point on the surface has the same potential.
Why is gravitational potential negative?
Work needs to be done to move the object outside of the field.
Since outside the potential is defined as 0, inside the field must be a negative.
How is the orbital period related to a radius of a circular orbit?
T² ∝ r³
compare the PE and KE of a lower orbit to higher orbit
lower orbit means smaller mass, means lower PE but higher KE.
Higher orbit means larger mass, more potential energy but less kinetic energy.
What is the period of a geosynchronous orbit?
Time period of 1 day = 24 hrs = 86400s
What is the period of a geosynchronous orbit?
Time period of 1 day = 24 hrs = 86400s
What is an escape velocity?
v = √ 2GM/r it is the minimum speed needed for an unpowered object to leave an orbit and not fall back into the gravitational field due to gravitatinal forces.
What is one application of geosynchronous orbits?
They are at the equator. useful for TV and telephone signals as you dont need to adjust the rciever or transmitter as the satellite already does that.
