1. Arinto Yudi Ponco Wardoyo
Physics For Astronomy
Arinto Yudi Ponco Wardoyo

2. Measurement Standard system SI – Standard International
Agreed in 1960 by International Committee
cgs – Gaussian System
US System

3. Basic Quantities and Their Units
Length [ L]
Mass [M}
Time [T]

4. Length
Units
SI : meter
cgs : centimeter (cm)
US Customary : foot (ft)
Defined in terms of a meter – the distance traveled by light in a vacuum during 1/ 299,792, 458 of a second

9. Astronomical Units Gravitation constant G=6,67x10-11 Nm2kg-2
Sun mass = 1,989 x1030 kg
Sun radius = km
Sun constant : Sun energy on the earth = 1380 w/m2
Sun luminosity = Lo= 3,86x1026J/s
Fsun bolometrict =6,28x107 Js-1m-2
Stefan Boltzmann constant, σ=5,67x10-8 Js-1m-2K-4
Earth mass = 5,975x1024kg
Earth radius = 6378 km
Gravity constant g=9,8 m/s2
Moon mass = 7,343x1023kg
Moon Radius = 1738 km
1 astronomical unit = 1,496x1011 m
1 parsec = 3,26x106 light year
Light velocity C = 3x105 km/s

16. IMPORTANT TO UNDERSTAND BASIC PHYSICS
Kepler’s Laws
Newton’s Laws (inertia, F=ma, equal and opposite reactions)
Gravity, Newton’s Universal Law of Gravitation
Surface Gravity
Circular motion and orbits
Centripetal Force
How to get masses from orbital speeds
Escape Velocity
Conservation of energy, kinetic energy, potential energy
Conservation of angular momentum

17. Angular Size

18. I drop a 10kg mass and a 5kg mass from 4 feet off of ground.
When to they hit?
a. same time
b. 10 kg mass hits first
b. 5 kg mass hits first
WHY? Hint: What is difference between mass and weight? Does acceleration due to gravity depend on mass?

19. How do you calculate the mass of a star if you can measure the orbital velocity of a planet orbiting around it?

20. What happens if the string breaks? (INERTIA!)

21. Calculating Escape Velocity
From Newton’s laws of motion and gravity, we can calculate the velocity necessary for an object to have in order to escape from a planet, called the escape velocity

22. Kepler’s Law