How does an object orbit something

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SUMMARY

This discussion focuses on the physics of orbital mechanics, specifically how objects, such as satellites, achieve and maintain orbit around a larger body like Earth. Key concepts include the necessity of achieving specific tangential and radial velocities for stable orbits, as well as the importance of launch angles. The discussion highlights that satellites experience a centripetal force directed towards the center of mass, which keeps them in orbit rather than moving in a straight line. Techniques such as the Hohmann transfer orbit are mentioned as methods to achieve circular orbits.

PREREQUISITES
  • Understanding of basic physics concepts, particularly forces and motion.
  • Familiarity with orbital mechanics and satellite dynamics.
  • Knowledge of velocity components: tangential and radial velocity.
  • Awareness of rocket propulsion and maneuvering techniques.
NEXT STEPS
  • Study the principles of Hohmann transfer orbits for efficient satellite launches.
  • Learn about the calculations involved in achieving specific tangential and radial velocities.
  • Explore the effects of launch angles on satellite trajectories.
  • Investigate the role of centripetal force in maintaining orbits.
USEFUL FOR

Students of physics, aerospace engineers, and anyone interested in understanding satellite dynamics and orbital mechanics.

ASidd
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I am having a very hard time understanding this concept in physics. Why would something orbit an object? Why doesn't it leave the orbit and move straight?

Also when a satellite leaves Earth how does it go into orbit? Does it have to be launched at a specific angle.
 
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Things can orbit because they experience a force that it at right angles to the direction they are traveling in.

You can see this on paper - mark a fat dot for the center of mass and a small dot for the satellite. Give the satellite a small random direction to travel. Now for each time interval, the satellite moves a small distance in the last direction it was headed in, but it is also attracted a small distance towards the fat dot. Try drawing that.

When a spacecraft goes into orbit, it's radial velocity has to reach zero and it's tangential velocity has to be right for the orbit. There are lots of ways of doing this - one way, indeed, involves being careful about the angle the rocket is launched. But recall, rockets are under power - they can, in principle anyway, manouver, and they can accelerate and decelerate. This gives more options.
 
ASidd said:
Why would something orbit an object? Why doesn't it leave the orbit and move straight?
Wiki article:

http://en.wikipedia.org/wiki/Orbit

ASidd said:
Also when a satellite leaves Earth how does it go into orbit? Does it have to be launched at a specific angle.
To get a satellite into a circular orbit normally requires at least two impulses, or one very long continuous (relatively low thrust) impulse. Wiki article:

Hohmann_transfer_orbit.htm
 

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