12 Gravitational Fields

Question 1

Polar orbit

Answer 1

Low altitude, high speed, used for google earth and weather

Question 2

Geostationary orbit

Answer 2

Remain above the same point of the earth at all times, time period of 24 hours

Question 3

Gravitational field

Answer 3

A region where a mass will experience a gravitational force

Question 4

Equation linking gravitational field strength, force and mass

Answer 4

g = F/m

Question 5

Equation for force between two masses and their separation

Answer 5

F = G x m1 x m2 /r^2

F = force between masses
G = gravitational constant 6.67x10^-11
r= distance between centre of mass of each object
m1 = mass of object 1 
m2 = mass of object 2

Question 6

Equation for earth’s gravitational field strength

Answer 6

g = GM/R^2

g = field strength
G = 6.67 x 10^-11
M = mass of earth
R = radius of earth

Question 7

Equation to find gravitational potential energy in uniform fields

Answer 7

GPE = mgh

Question 8

Equation to find gravitational potential energy in radial fields (learn)

Answer 8

GPE = -GMm/r

G = 6.67 x 10^-11
M = mass of earth
m = mass of object
r = distance between their centre of masses

Question 9

Equation to work out gravitational potential

Answer 9

Vgrav = -GM/r

G = 6.67 x 10^-11
M = mass of earth 
r = distance from point to centre of earth

Question 10

Differences between G fields and E fields

Answer 10

• G fields act on mass, E fields act on charge

* G fields only attract, E fields attract and repel

Question 11

Equation linking speed of orbit, mass of planet and distance from centre of mass (learn)

Answer 11

V^2 = GM/r

V = speed of orbit
G = 6.67 x 10^-11
M = mass of planet
r = distance from centre of mass

Question 12

Equation linking time period of orbit, mass of planet and distance from centre of planet (learn)

Answer 12

T^2 = 4pi x r^3/ GM

T = time period
r = distance from centre of planet
G = 6.67 x 10^-11
M = mass of planet