12. Gravitational Fields Flashcards
What is a force field?
An area in which an object experiences a non-contact force.
What does the distance between field lines denote?
The strength of a force exerted by the field in that region.
What is a gravitational field?
A force field in which objects with mass experiences a force.
Describe a uniform field?
- Same gravitational force is exerted on a mass everywhere in a field.
- Field lines same direction
- Field lines equally spaced.
Describe a radial field?
- Force exerted depend on the position of the object in the field.
- Field lines all away or all towards a central point.
What is gravitational field strength
The force per unit mass exerted by a gravitational field on an object.
What are features of gravity?
- Acts on objects with mass.
- Always attractive.
What is gravitational potential?
The work done per unit mass when moving an object from infinity to a point.
What it the gravitational potential at infinity?
Zero.
V = - GM/r
What is the significance of the negative?
As an object moves from infinity to a point, energy is released as GPE is reduced.
What are the similarities and differences between electric and gravitational fields?
Similarities:
- Both follow an inverse-square law.
- Use field lines to represent and can both be uniform or radial.
- Use equations of similar form to find the force exerted and strength of field.
Differences:
- Gravitational forces exerted is always attractive, whilst electric fields they can also be repulsive.
- Electric forces act on charges, whilst gravitational acts on masses.
What is kepler’s third law?
The square of the orbital period (T²) is directly proportional to the cube of the radius (r²).
