# {Year 2} Chapter 3 - Gravitation (Halfway down pg47) Flashcards

Why does the moon have a smaller surface gravity than the Earth?

As it is a less massive body

What is Newton’s Law of Gravitation?

F = (m1)(m2)G / r^2

What is G?

The universal constant of gravitation - 6.67 x 10^-11

When can Newton’s Law not be applied, and why?

When the two masses are irregularly shaped unless a complicated summation of the forces is made - since the law only works for point masses, or spheres since they act as if their mass was concentrated in the middle

What law does gravity, like light, obey?

The inverse square law

What is a gravitational field?

A region in space in which a massive object experiences a gravitational force

What is field strength?

The strength of the gravitational field measured in N/kg. Field lines represent the direction and strength of the field

What is the equation for gravitational field strength?

g = F/m

What happens to the gravitational field near the surface of a planet?

It becomes very nearly uniform - meaning that the field is of the same strength and direction everywhere

What is the difference in the way gravitational field lines are drawn when the field is half as powerful?

The lines are half as prevalent/half as many of them

When is capital M used in equations in gravitation?

For the mass of a large object such as a star or a planet

What is the equation for the volume of a sphere?

V = 4/3 x Pi x r^3

What is the equation for gravitational potential energy?

Grav. pot. = mass x gravity x difference in height

What is gravitational potential difference?

The gravitational potential energy difference per kilogram. Gravitational potential and potential difference have units of J/kg. It’s symbol is Delta V

What is an equipotential surface?

A surface along which if you move, the gravitational potential stays the same