1. Mass of a Celestial Body
Physics 20
Mass of a Celestial Body

2. Determining the mass of a Celestial Body
For any satellite in orbit around a planet, you can determine its speed if you know the mass of that planet. But, how do you determine the mass?
Fc = Fg according to Newton so …
4π2mmoonr = GmmoonmEarth Solve for mEarth
T2 r2
This is not restricted to the Earth-moon system. It will work for any celestial body that has satellites
Knowing this calculate the mass of earth.

3. Orbital Perturbations
Irregularity or disturbance in the predicted orbit of a planet
Was essential in discovering the planets in our outer solar system and now discovering other planets orbiting other suns
Uranus had an orbital perturbation and because of this Neptune was found.

4. Assignment Reading: Questions: Pearson Physics Pgs 280 – 286
Pearson PhysicsPg 286 text - #13
SNAP Pg282 #’s 6, 9

5. Hand In assignment Decision Making Analysis 5-5 (Pg 284) Groups of two
Use info from pages 284 – 286
Find info on the web
Sites to try – NASA
- Canadian space program (CSA)
Groups of two
Part of your assignment and lab mark