Gravitation Simulation Lab Name: _________________________________
Purpose: To gain familiarity with the nuances of the gravitational force; To understand what variables affect it's strength; To show how the
gravitational force controls the motions of the planets; To understand how orbital velocity is affected by distance.
Background: According to Newton's Universal Law of Gravitation, the mass of an object, its distance from another object, and the mass
of the other object all affect the magnitude of the gravitational force between them. For an object to maintain a stable orbit around
another, it must have enough horizontal velocity to keep its radial acceleration from succeeding in pulling the object closer to the sun.
Once defined, two objects orbiting each other are stable and will keep doing so indefinitely. Three or more bodies in orbit are inherently
much less stable and often tend to keep colliding until only two are left.
Procedure: Go the the University of Colorado web site and run the "My Solar System" gravitation simulation (click on
link or use http://phet.colorado.edu/simulations/sims.php?sim=My_Solar_System)! Set the "accurate-fast" slider to its middle position.
Check the "system-centered" and "show traces" boxes. Then, use the program to set Solar System
up the following situations and answer the following questions. Body Mass x y vx vy
1) Solar System: Choose 4 bodies. Fill in the initial settings table with the following 1 800 -87 0 0 0
data. Start the simulation and observe it for a while. 2 10 3 0 0 300
3 10 136 0 0 190
a) What do you notice about the velocities of the three "planets"? What 4 10 249 0 0 160
general rule can you state?
2) Comet: Choose two bodies. Fill in the initial settings table with the following data. Comet
b) How does this orbit compare to that of a typical planet? Body Mass x y vx vy
c) Use the tape measure and find the eccentricity of this orbit. 1 800 -360 0 0 0
d) How does comet speed relate to the comet's position in the orbit? 2 4 383 0 0 25
3) Escape Velocity: Choose four bodies. Fill in the initial settings table with the Escape Velocity
following data. This simulation shows the effect of different orbital velocities for Body Mass x y vx vy
planets at essentially the same distance from the sun. 1 500 212 -50 0 0
e) How does speed affect the shape of an orbit (when r is constant)? 2 0.1 212 149 -70 0
f) If enough speed is given, what will the object do?
3 0.1 212 162 -152 0
4 0.1 212 175 -220 0
4) Moon on Moon: Choose four bodies. Fill in the initial settings table with the Moon on Moon
following data. Notice the strange pattern traced by the smallest moon. Body Mass x y vx vy
g) What causes the strange shape of the trace ? 1 400 -101 -32 0 0
h) What do the large moon and the planet rotate around? 2 60 169 -32 0 130
5) Slingshot: When space probes are sent out of the solar system, they do not leave earth 3 9 234 -32 0 30
with the 45km/s velocity needed to escape the sun's gravitational pull. Instead, they
4 .01 221 -32 0 -26
use the gravitational force to transfer some momentum (and KE) from a planet to Body Mass x y vx vy
themselves. Run this simulation and assume that the turquoise object is the space 1 200 1 0 0 0
probe, while the purple object is a large planet (like Jupiter). 2 10 131 55 -55 115
i) How is the probe's motion different before and after the planetary 3 1 -6 -128 80 0
encounter? What happens to its mechanical energy? Chaos
j) What happens Jupiter's mechanical energy as a result of the encounter? Body Mass x y vx vy
How can you tell? 1 800 -123 -60 0 -1
6) Chaos: Choose four bodies. Give them the masses and positions indicated in the 2 40 46 -60 0 148
table. Start the simulation. 3 40 170 -60 -1 126
4 40 304 -60 0 90
k) Describe what happens.
l) Is the sun's gravitational force on a planet the only force that affects its motion/orbit?
m) Could this ever happen in our own solar system? Why? Practice
7) Practice: Choose four bodies. Give them the masses and positions indicated in the Body Mass x y vx vy
1 400 -217 -32
table. Start the simulation. What happens? Now try giving the three planets velocity. 2 20 -93 -32
Start small then increase. After each increment, hit the start box and watch how your 3 20 -430 -32
velocity adjustments have affected the motion of the planets. Aim at first for 4 20 177 -32
elliptical orbits and then try to get circular ones. When you have succeeded in producing planets with stable, circular
orbits, record their velocities.
8) Three body system: In this lab, it is your mission to invent a three body system that lasts for a minimum of 150 seconds.
All three objects must be massive and they must not ever collide or be sent off forever into interstellar space. Create
planets, assign them masses, and adjust their relative positions and velocities in order to achieve this end. ALL THREE
OBJECTS MUST BE MASSIVE, with at least two of the bodies having a value of
500 or greater. The third must have a minimum mass of 100. When you have Three Body System
Mine succeeded, record the data in the table. Body Mass x y vx vy
Body Mass x y vx vy
1 500 -285 0 0 -120 2
2 800 85 0 0 170
3 600 210 0 0 -50 3
What do the arrows on a gravity map mean?They are vector arrows that communicate visually the magnitude (size) and the direction of the force. True or False 1. Gravity is a force that can be changed. T/F 2. The more mass an object is, the smaller the force of gravity. T/F 3. As one object gets closer to another object, the force of gravity will increase.
Title: Gravitation Simulation Lab
Author: ALDESA Puesto de Bolsa S.A.
Creator: Microsoft® Word 2016
Producer: Microsoft® Word 2016
CreationDate: Fri Apr 26 09:58:15 2019
ModDate: Fri Apr 26 09:58:15 2019
Page size: 612 x 792 pts (letter) (rotated 0 degrees)
File size: 267416 bytes
PDF version: 1.5