Unit 4.2 - Electrostatic and gravitational fields Flashcards
What’s similar about electrostatic and gravitational fields?
Both have very similar forms
What does the gravitational field of the earth provide?
A constant acceleration of 9.81ms^-2
When is using the constant acceleration of 9.81ms^-2 from the gravitational field of the earth a useful method?
When we consider small changes in height above the surface of the earth
What is a field in physics?
A model of a physical quantity, typically a number, that has a value for each point in space and time
Scalar fields
Will have a value only at different points
Example of a scalar field
The temperature at different positions around the country
Vector fields
Have a value and a direction related to their position
Describe and give an example of a vector field
On a weather map, the surface wind velocity is described by assigning a vector to each point on a map. Each vector represents the speed and direction of the movement of air at that point.
What is a gravitational field?
A model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body (a body that has mass)
= force per unit mass
What is used to explain gravitational phenomena?
A gravitational field
What is a gravitational field measured in?
Newtons’s per kilogram
How has the way gravity has been explained changed over time?
Original concept —> gravity was a force between point masses
Then —> gravity was some kind of radiation field or fluid
Now —> gravity is taught in terms of a field model rather than a point attraction
Describe what a field model is and what happens in it
Rather than two particles attracting each other, the particles distort space-time via their mass, and this distortion is what is perceived and measured as a “force”
What is measured as a force in a field model?
Particles distorting space-time via their mass
What does mass do to space-time?
Curves it
Describe space- time when there’s no mass
Flat
Describe space-time where there is a mass
Curvature towards the mass
What will happen to two masses in a field model and why?
Will attract each other due to the curvature caused by the mass
Where will masses fall in the field model with a large and small mass?
The smaller mass will fall towards the large mass
How does matter move in the field model?
In certain ways in response to the curvature of space-time
Describe the gravitational force in the field model
There is either no gravitational force or gravity is a fictuous force
Way of imagining the field model
Consider a heavy mass on a flexible surface
What is the only thing that’s significant to the object causing the curvature of space-time in field model?
The mass of the object
What is not significant to the curvature of space-time caused by an object in the field model?
The size of the object