Planetary Motion and Gravity

Question 1

What creates stable elliptical orbits?

Answer 1

Gravity!!!!!

Question 2

What are Keplers laws of planetary motion?

Answer 2

1. The planets move in stable elliptical orbits around the sun
2. Equal areas around a planets orbit sweep out equal intervals of time( if A1=A2, then t1=t2)
3. t squared/r cubed = a constant that is dependent on the mass of the central body

Question 3

Define aphelion, perihelion, apogee and perigee

Answer 3

For Solar orbits, aphelion is the furthest point from the star on a planets orbit, perihelion is the closest point
For Earth orbits, apogee is the furthest point from the Earth on the moons orbit, perigee is the closest

Question 4

Keplers third Law

Answer 4

T squared/r cubed = constant K which depends inversely on the mass of the central body M
K1M1 = K2M2 or KM = constant

Question 5

What did Newton do?

Answer 5

He linked falling apples to the orbit of planets and “discovered gravity”. His law of universal gravitation was able to explain Kepler’s laws.

Question 6

How does gravitational force relates to bodies’ masses and separation?

Answer 6

Gravitational force between two bodies is proportional to the product of their masses
It is inversely proportional to the square of their seperation