Topic 8- Planetry Motion And Gravity Flashcards
Who put forwards the heliocentric model
Copernicus
What book did Copernicus write
De revolutionibus orbium coelestium- on the revolutions of heavenly spheres
What types of orbits did the planets have in Copernicus’ book
Circular orbits
What type of observations supported his theory
Mathematical observations
When was the book published
After he died
Why did people find it hard to accept the heliocentric theory
It went against what the bible said
What model did Tycho Brahe propose
The geo-heliocentric model
What is the geo-heliocentric model
The moon and sun orbited the earth but everything else orbited the sun
What did tychos base his model on
Both religious and on observations
Who was Kepler
Tycho Brahe’s assistant in Prague
Who was Kepler influenced by
Copernicus
What did Kepler refine
The heliocentric model
What did Kepler notice with tychos observations
He noticed that planets did not follow circular orbits but we elliptical
What was Galileo Galilei first to do
The first telescopic observer to make published astronomical observations
What did Galileo discover
Jupiter has moons
Venus had phases
What happened because of Galileos observations
The heliocentric model became widely expected
What force is responsible for creating stable elliptical orbits
Gravity
How does gravity create stable elliptical orbits
Due to the constant gravitational force between the object and the sun to keep it in orbit
What are the 2 things that control gravity
Mass and distance
What is keplers first law
Planets do not move in circular orbits
What is an ellipse
An oval shape with 2 foci
What are the 2 foci
The sun and the other is in space
What is keplers second law
The sun-planet line sweeps out equal areas in equal times
Does a planet move faster or slower when near the sun
Faster
What is keplers 3rd law
The orbital period of a planet squared is equal to its mean distance from sun cubed when different planets are compared
How do you work out a constant
T2/R3
What does the T stand for in the constant equation
Period/time takes to orbit/ orbital period
What does the R mean in the constant equation
Mean radius from the body it’s orbiting
Who proposed the inverse square law
Newton
What is the inverse square law
If earth had a 1/2 of its mass then it would produce 1/4
What was the relation to keplers law
For every action there is an equal action and opposite reaction
If an object orbits nearer another in an elliptical orbit there must be an increase or decrease in gravitational force between them at that point
Increase
What is keplers 3rd law
The force is proportional to the sum of the masses of both objects it inversely relies on the mass of the sun essentially
What does perihelion mean
Body nearer the sun
What does aphelion mean
Body further away from sun
