Gravitational and Electric Fields Flashcards
What type of field is a gravitational field?
A gravitational field is a force field
What is a force field?
- A force field is a region where an object will experience a non-contact force
- Force fields cause interactions between objects or particles or in the case of gravity, between masses
What type of quantity is a force field?
A vector quantity
What happens when an object is put in the gravitational field of another object?
Any object with mass will experience an attractive force if you put it in the gravitational field of another object
How can you represent the force field around an object?
Force fields can be represented as vectors showing the direction of the force they would exert on an object placed in that field. Gravitational field lines are arrows showing the direction of the force that masses would feel in a gravitational field
How can you tell the direction of the force in a force field diagram?
The direction that the arrows are pointing in shows the direction of the force
What would happen if you put a small mass anywhere in the Earth’s gravitational field?
If you put a small mass anywhere in the Earth’s gravitational field it will always be attracted towards the Earth
What type of field is the Earth’s gravitational field?
The Earth’s gravitational field is radial - the lines of force meet at the centre of the Earth
Explain in terms of field lines the effect on the force felt by a mass in the Earth’s gravitational field if it were moved further away?
If the mass is moved further away from the Earth where the lines of force are further apart the force it experiences decreases
Why does the gravitational field of a small mass in the Earth’s gravitational field not affect the Earth?
The gravitational field of the mass does not affect the Earth as the Earth is much more massive
How is an uniform field represented on a field line diagram?
The field lines are parallel and equally spaced
Define a gravitational force field
A region in which an object with mass experiences weight
State the equation given by Newton’s Law of Gravitation and each variable
F = Gm1m2/r^2
- G is the gravitational constant
- m1 and m2 are the respective masses of the objects involved
- r is the distance between the centres of the two masses in metres
- F is the magnitude of the gravitational force between masses m1 and m2
State Newton’s Law of Gravitation
The gravitational force of attraction between two masses is inversely proportional to the distance between their centre of masses squared and is directly proportional to the product of the two masses
What would happen to the force between two objects in a gravitational field if the distance r between two masses increases?
As Newton’s law of gravitation is an inverse square law, F ∝ 1/r^2
If the distance r between the masses increases the force F will decrease
What would happen to the force between two objects in a gravitational field if the distance between them doubles?
If the distance between two objects in a gravitational field doubles then the force will be one quarter of the original force
What does the gradient of a force-mass graph tell us?
The gravitational field strength
Define gravitational field strength
The gravitational field strength at a point in a gravitational field is the force acting per unit mass at that point
What is the formula for calculating the gravitational field strength of a uniform field?
g = F/m
- F is the force experienced by a mass when its placed in a gravitational field
- Units are N/kg
What is the gravitational field strength at a point equal to?
The gravitational field strength at a point is equal to the acceleration due to gravity at the point
What type of quantity is gravitational field strength?
A vector quantity
What is the formula for calculating the gravitational field strength in a radial field and what are the variables?
- g = GM/r^2
- G is the gravitational constant
- M is a point mass (kg)
- r is the radius of the mass (m)
What type of objects have a radial field?
Spherical objects
What type of relationship does gravitational field strength and distance have?
They have an inverse square law relationship meaning that as r increases, g decreases