chapter 7: gravitation

Question 1

What are the three kepler’s laws

Answer 1

1. Law of orbits
2. Law of areas
3. Law of periods

Question 2

Define Kepler’s first law

Answer 2

Law of orbits
All the plante move in elliptical orbits with the Sun situated at one of the foci.

ellpises are NOT circles, low eccentricity - nearly a circle

Question 3

The point closest to the sun and point farthest to the sun is called?

Answer 3

Perihelion and Aphelion

Question 4

Define second Kepler’s law

Answer 4

Law of areas
The orbital speed of a planet depends on the distance from the sun.
Planet sweeps up equal areas in equal intervals of time.

the planet slows down when further away, speeds up when its closer to the sun

Question 5

Define third Kepler’s law

Answer 5

Law of periods
The square of any planet’s orbital period (T) will be propotional to the cube of the semi-major axis of the ellipse traced out by the planet (a)

T^2 ∝ a^3

Question 6

Explain Universal Law of Gravitation

Answer 6

Every body in the universe attracts every other body with a force which is directly propotional to the product if their masses and inversely propotional to the sqaure of the distance between them
F=G(m1×m2) / (r^2)

F = force
G = gravitational constant
m1 = mass of object 1
m2 = mass of object 2
r = distance between centers of the masses