1. 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 = 700 000 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