Why Don’t Satellites Fall to Earth Despite Constantly Falling?

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Discussion Overview

The discussion centers on the mechanics of satellite orbits and the nature of gravitational forces acting on orbiting bodies. Participants explore why satellites and planets do not fall into the Earth or the Sun despite being under the influence of gravity, addressing concepts of acceleration, momentum, and the relationship between tangential speed and gravitational pull.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why the falling velocity of a satellite does not increase radially, suggesting that gravity should cause continuous acceleration towards the Earth.
  • Another participant clarifies that acceleration can refer to changes in direction, noting that satellites are constantly changing direction as they orbit.
  • It is proposed that planets would fall into the Sun if they lacked sufficient forward momentum, which balances gravitational pull, allowing for stable orbits.
  • A participant reiterates that without forward momentum, planets would not maintain their orbits and would instead move in a straight line if gravitational forces were removed.
  • One participant expresses confusion about why the velocity of a satellite remains constant despite gravitational acceleration, drawing a comparison to falling objects in the atmosphere.
  • A later reply emphasizes that velocity, being a vector, changes due to the constant change in direction, which constitutes acceleration.

Areas of Agreement / Disagreement

Participants express differing views on the nature of velocity and acceleration in orbital mechanics. While some clarify the role of momentum and direction in maintaining orbits, others remain uncertain about the implications of gravitational forces on speed and acceleration.

Contextual Notes

There are unresolved questions regarding the definitions of acceleration and velocity in the context of orbital motion, as well as the assumptions about gravitational effects in different environments (e.g., atmosphere vs. space).

john fairbanks
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when a satalite orbits the Earth my text states that it is constantly falling into the Earth as it moves tangentially -- my question is why doesn't the speed of the object falling into the Earth increase radially since it is acted upon by the force of gravity, a force of gravity would cause an object to accelerate! so the falling velocity should not be constant like the tangential speed -- in fact all planets should fall into what they are orbiting around. But they don't so please help!:confused:
 
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Keep in mind that 'acceleration' can mean a change of direction just as properly as a change of speed. A satellite is constantly changing direction as it follows the curvature around its parent.
 
The planets would fall into the sun if they had no "forward" momentum. Think of what would happen if the sun suddenly disappered. The Earth would just go in a straight line tanget to the previous orbit. A planet orbits because it has enough forward momentum to exacly balance the pull of gravity.
 
The planets would fall into the sun if they had no "forward" momentum. Think of what would happen if the sun suddenly disappered. The Earth would just go in a straight line tanget to the previous orbit. A planet orbits because it has enough forward momentum to exacly balance the pull of gravity.
 
Thnaks for responding, they move tangent to the orbit at a uniform velocity but the force of gravity should accelerate the satellite or planet, just like in our atmosphere, speed increases as a body falls due to gravity. it accelerates, the fall is not a constant speed -- so why does the velocity of the fall of a satellite stay the same. du to accelerationdarisI kno
 
john fairbanks said:
Thnaks for responding, they move tangent to the orbit at a uniform velocity but the force of gravity should accelerate the satellite or planet, just like in our atmosphere, speed increases as a body falls due to gravity. it accelerates, the fall is not a constant speed -- so why does the velocity of the fall of a satellite stay the same. :confused:
 
The velocity does not remain the same. Velocity is a vector (it entails both speed and direction). Since the direction is constantly changing, so is the velocity... which is the definition of 'acceleration'.
 

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