https://phet.colorado.edu/sims/html/gravity-and-orbits/latest/gravity-and-orbits
ID: 3281206 • Letter: H
Question
https://phet.colorado.edu/sims/html/gravity-and-orbits/latest/gravity-and-orbits_en.html
book ref: physics and technology for future presidents
Question 3
What is the nature of the orbit (geometrical shape) and the acronym you would give it (LEO, GEO, MEO, HEO)? Refer to lecture slides of lecture 11 week 7.
What is the time it takes the satellite to go around the Earth once (time period of the orbit)?
What is the farthest distance from the Earth that the satellite went (hopefully you can see this on the screen; if not bring the initial point of the satellite a little closer to Earth, but not as close as 1 Grid square, and try again).
How does the orbital period compare with that you found in your answer to question 1?
What happens if you move the satellite too far away from the Earth?
Question 4
Divide the time that your satellite is spending in the modified orbit you found above into two parts: (i) the part which corresponds to Earth-satellite separation close to the initial separation (when you started the orbit close to Earth), and (ii) the part where the satellite is much farther away from the Earth.
How do the times the satellite spends in these two parts compare?
Which one of the three Kepler’s laws explains the difference in these times (refer to lecture 10 slides in week 7 folder to review the three laws)?
Question5
Return to the initial position of the satellite you found above (which is more than a grid square away from Earth’s center) by pressing the "forward" button. Change the size of the velocity arrow (orange arrow) by dragging it so that the resulting orbital path is circular. Once you have obtained this new circular orbit you have created a MEO orbit.
How does the time the satellite spends in the MEO you found above compare with the time it spent in the orbit you found in answering question 4?
GPS satellites can be launched in either circular orbits (MEO) or HEO orbits. With GPS satellites you want a network of satellites to be above a region for a long time. Keeping this fact in mind discuss the advantage/disadvantage of using a HEO orbit over a MEO orbit for setting up a GPS system.
Explanation / Answer
Q3. LEO : Low Easrth Orbit, is orbit around earth at an altitude of about 1200 mi or less
the shape of the orbit is elliptical
time taken to move around the earth is about 170 minutes
the farthest distance form the surface of earth is about 3900 mi for cloasest distance of 1200 mi
GEO : Geostationary Earth Orbit, is orbit around earth at an altitude of about 22236 mi
the shape of the orbit is circular
time taken to move around the earth is about 24 hours
MEO : Medium Earth Orbit, is orbit around earth at an altitude of about 22,000 mi or less, but greater than 1200 mi
the shape of the orbit is elliptical
time taken to move around the earth is about 360 minutes
the farthest distance form the surface of earth is about 11000 mi for cloasest distance of 2000 mi
HEO : Highly elliptic Orbit, is orbit which is higly elliptic with eccentricity of about 0.2 or 0.3
the shape of the orbit is elliptical ( higly elliptical)
if the satellite is taken too far away from the earth it starts getting influenced by the gravitation of other planets and has a greater tendency to break away form the orbit of the earth
Q4. so the satellite spends more time in the part where is is fartther from the earth, this means that the satellite moves slower when farther from the planet
this obeys the kepler's law whgich states that the area swept bu the line joining the center of the satelite to the center of the orbit per unit time remains constant
Q5. MEO orbit or a GEO orbit both can have a time period of about 24 hours where they spend most of the time on one locatino of the planet and are circular in shape but HEO orbit has a high eccentrity due to which its distance form the surgface of the planet keeps on changing a lot making it difficulkt for the signals to be accurately measured in time doimain which is imprtant for GPS navigation and hence MEO orbits are better for GPS application then HEO orbits
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