Gravitational Fields Flashcards
What is a field force?
A region in which a body experiences a non contact force
What is r is ‘force between two masses’ equation?
Distance between centres of objects
What is the force on m1 due to m2 equal to?
Minus the force on m2 due to m1
What happens to acceleration as force increases?
It increases ( F = ma )
What does spread of field lines show?
Field strength at that point
What is gravitational field strength?
The force per unit mass experienced by a body in a gravitational field (always points towards a masses centre)
What is area under g-r graph?
Gravitational potential
What does adding gravitational field strengths up do and why can you do this?
Shows the combined effect of objects (gravitational field strength at a point). Gravitational field strengths are vectors so you can do this.
What is escape velocity and the equation?
The min speed an unpowered object must have to leave the gravitational field of a planet and not fall back towards the planet due to gravitational attraction.
V = (2GM/r)^0.5
Why is gravitational potential negative?
- At r = infinity, potential = 0
- energy needed to move to infinity
- therefore work is done by a field moving the object from infinity
- potential energy falls as an object moves from i infinity
What happens when you move an object?
Work is done against gravity
Why is there a gravitational potential difference between two objects?
Objects at different points in a gravitational field have different potentials
What is a satellite?
A smaller object that orbits a larger mass (kept in orbit by centripetal force)
Why are potential and kinetic energies of a satellite constant?
Because the orbit speed is constant (greater r = slower orbit speed)
Equal centripetal force and force between two masses?
Find time period
