Gravitational Fields

Question 1

Gravitational field strength

Answer 1

force per unit mass

Question 2

Newton’s law of gravitation

Answer 2

the gravitational force between two masses is proportional to the product of the masses and inversely proportional to the distance squared between them

Question 3

Deriving Kepler’s law

Answer 3

Equate the centripetal force to gravitational force.
x by r.
substitute centripetal velocity then rearrange for T^2.

Question 4

Kepler’s third law

Answer 4

the cube of the planets distance from the sun divided by the square of the orbital time period is the same for all planets

Question 5

Geostationary Orbit

Answer 5

an equatorial orbit with a time period equal to the rotation period of the earth and in the same direction as the earth’s rotation

Question 6

Uses for geostationary satellites

Answer 6

Radio communications, spying

Question 7

which equation can be used to find the force between two point masses or spherical objects

Answer 7

F= (GMm)/r^2

Question 8

Equation for gravitational field strength, or to determine the mass of the earth

Answer 8

g= (GM)/r^2

Question 9

describe the gravitational field strength of the earth

Answer 9

close to the surface it is uniform and approximately equal to the acceleration of free fall

Question 10

How/why do you use the inverse square law

Answer 10

to analyse circular orbits by relating the gravitational force to the centripetal acceleration it causes

Question 11

How can Kepler’s third law be used to solve problems?

Answer 11

T^2 α r^3 which can be used for planets and satellites