Gravitational Fields Flashcards
What objects experience a greater force due to gravity?
Objects with more mass
How does the force due to gravity on earth change in relation to distance ?
It gets weaker as you get further away
What is newtons law of gravitation ?
the gravitational force of attraction between 2 point masses is separated by a distanace r
What is a gravitational field?
A region in space in which a massive object experiences a gravitational force
What is gravitational field strength and how is it represented?
The strength of the field which is measured in N/kg and field lines represent the direction and strength
What is a uniform field ?
The field is the same strength and direction in the whole area
How do field lines show a stronger field ?
When the field lines are closer together
Describe the gravitational field lines around a planet
Radial, equally spaced if uniform, pointing inwards
What is gravitational potential?
The work done per unit mass against gravitational force to move an object from infinity to a given point
What is the unit of potential energy ?
J/kg
What are equipotential lines ?
Lines that link points of equal potential
Equipotenital surfaces are always___________________to the gravitational field
At right angles / perpendicular
What happens when something moves along the equipotential lines ?
As it is travelling perpendicular to the field, no work is done so there is no potential energy change
What happens when something moves along a field lines?
It is moving parallel to the field so work is done so there is a change of potential energy
Why is the potential gradient negative?
Because potential increases as height increases so the field direction is downwards
What is escape velocity?
The minimum velocity an object must have at the surface of a planet to escape the pull of gravity using its own kinetic energy
When is the potential 0?
At infinity
What equations do you equate to calculate escape velocity?
Kinetic energy and gravitational potential energy
What equations do you use for orbits?
circular motion and gravitational
What is a synchronous orbit?
Where the orbital period of the satellite is equal to the rotational period of the object that it is orbiting. e.g. for earth its period would be 24 hours
What objects does gravity act on?
Objects with mass
Is Gravity attractive or repulsive?
Always attractive
What happens when a object is moved from infinity to a point?
Energy is released as the gravitational potential energy is needed, therefore gravitational potential is always negative
What is gravitational potential difference?
The energy needed to move a unit mass between two points
