P2 - Gravitational feilds

Question 1

what is a gravitational field?

Answer 1

any object with mass will experience an attractive force if you put it in the gravitational field of another object. A gravitational field is a force field.

Question 2

What does the distance between gravitational field lines show?

Answer 2

strength of the field

Question 3

What does big G stand for in newtons law of gravitation equation? r?

Answer 3

G = grav constant

Distance between the centres of the two masses

Question 4

How does the inverse square law take affect in grav fields?

Answer 4

as distance between points increases, force between two points decreases at a great rate as the r is squared

Question 5

What is grav field strength defined as?

Answer 5

gravitational field strength, g is the force per unit mass. its value depends on where you are in the field.

Question 6

what is gravitational potential?

Answer 6

The gravitational potential, V, at a point is the gravitational potential energy that a unit mass at that point would have.

Question 7

How does distance from the surface of a large object effect gravitational potential energy’s strength?

Answer 7

gravitational potential energy is negative on the surface of the mass and increases with distance from the mass. as you have to do work against the field to move an object out of it. This means that gravitational potential at an infinite distance away from the mass will be zero.

Question 8

What is does the area under a r g graph represent?

Answer 8

change in V

Question 9

What is gravitational potential difference?

Answer 9

gravitational potential difference is the energy needed to move a unit mass. two different points in a grav field will have different potentials so there is a difference between them. work is done against gravity.

Question 10

What does Ep stand for?

what does v stand for?

Answer 10

gravitational potential energy

gravitational potential

Question 11

what is the gravitational potential energy equation for an object of mass m?

Answer 11

• GMm/r

- Big G, BigM, little m, over r

Question 12

what is a equipotential in terms of grav fields?

Answer 12

are lines that you travel along where v does not change so you don’t lose or gain energy so work done is zero
field lines and equipotential are always perpendicular

Question 13

what is a satellite?

Answer 13

A satellite is any smaller mass that orbits a much larger mass.
Kept in orbit by grav forces that act as centripetal force

Question 14

what is the equation for orbital speed?

Answer 14

v = root big G big M over r 
v = root GM/r

Question 15

what is the equation for orbital peroid?

Answer 15

Tsquared = 4piesquared r cubed over big M big G 
T^2 = 4pie^2 r^3/MG

Question 16

what is a orbiting satellite’s energy made up of?
what is the energy in a circular orbit like?
What is it like in an elliptical orbit?

Answer 16

kinetic and potential
kinetic and potential are constant so speed and distance is constant
In a elliptical orbit a satellite will speed up as its orbital radius decreases and slow down as its orbital radius increases. So its kinetic energy increases as its potential energy decreases

Question 17

What is escape velocity?

Answer 17

escape velocity is the minimum speed an unpowered object needs in order to leave the gravitational field of a planet and not full back due to gravitational attraction

Question 18

What is the escape velocity equation?

Answer 18

velocity = root, 2 Big G, Big M over r 
v = root 2GM/r

Question 19

What is a synchronous orbit object? example of this? how is this achieved? what is it useful for?

Answer 19

is when an orbiting object has an orbital period equal to the rotational period of the object it is orbiting. Geostationary satellites are examples of this, their orbit must be in the plane of the equator of the earth. very useful for TV and telephones signals.

Question 20

What is a low orbiting satellite? what uses?

Answer 20

a satellite that is low to the earth

mapping, spying