Gravitational And Electrical Fields Flashcards
What is a force field?
A region in which a body experiences a non-contact force
What is newtons law of gravitation?
The force between 2 masses is proportional to the product of the 2 masses. The force is inversely proportional to the distance between their centres squared. The force is always attractive
What is the inverse square law?
If the distance between 2 objects halves, the effect of the force quadruples
What do gravitational filed lines show?
They show the direction and relative magnitude of the force a mass at that point will feel
What is gravitational field strength?
The force felt by a 1kg mass at that point in the field
What is gravitational potential?
The work done per unit mass in moving a mass from infinity to a point (always negative)
Why is gravitational potential always negative?
Gravitational potential is defined as 0 at infinity, and work must be done on a mass to move it from a point in the field to infinity, therefore potential is negative
What is an equipotential line?
Points where the potential is the same, these lines are always at right angles to the field lines
What is given by the gradient of a graph of potential against distance?
Field strength (need a tangent)
What is given by the area under a graph of field strength against distance?
Potential difference
What is meant by escape velocity?
The minimum speed an unpowered object needs in order to leave the gravitational field of a planet
What is a geostationary orbit?
An orbit which has the same orbital period as the earth, and remains at the same point on the earths surface
State the ratio of the radius of the earth to the moon
3.6-3.7
State the radius of GEO
42000 km
State the height of GEO
36000 km
What is Coulomb’s law?
- the force between 2 charges is proportional to the product of the charges
- the force is inversely proportional to the distance between their centres squared
- force can be attractive or repulsive
What do electric field lines show?
They show the direction and relative magnitude of the force of a positive charge at the point will feel
Fora charged particle entering a uniform electric field at right angles, what shape does the path follow?
Parabolic
What is electric potential?
The work done per unit charge in moving a positive charge from infinity to the point (always positive if negative charge creating the field, and always negative is positive charge creating the field)
What does it mean when field lines are converging in a uniform field?
There is a stronger point in the field
What can air be treated as when using Coulomb’s law?
A vacuum
