Why does a falling object experience constant acceleration due to gravity?

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Discussion Overview

The discussion revolves around the concept of constant acceleration due to gravity for falling objects, specifically addressing why objects continue to accelerate at 9.8 m/s² until reaching terminal velocity and the role of air resistance in this process.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants express confusion about why a falling object continues to accelerate at 9.8 m/s² rather than just accelerating once until reaching terminal velocity.
  • There are questions regarding the impact of air resistance on the acceleration of falling objects, with some participants suggesting that air resistance does not affect the acceleration as long as terminal velocity is not reached.
  • One participant clarifies that air resistance acts as a retarding force and that the total acceleration is determined by the net force acting on the object, as described by Newton's Law (ΣF = ma).
  • Another participant elaborates that when the forces of gravity and air resistance are equal, the total force becomes zero, resulting in zero acceleration and the establishment of terminal velocity.

Areas of Agreement / Disagreement

Participants express differing views on the role of air resistance in the acceleration of falling objects, indicating that the discussion remains unresolved regarding the nuances of how these forces interact.

Contextual Notes

Some statements reflect assumptions about the conditions under which air resistance affects acceleration, and the discussion does not clarify the specific scenarios being considered, such as the range of velocities or the characteristics of the objects involved.

BRH
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I know that there is constant acceleration due to gravity. A regular force that is applied to a moving object causes the object to accelerate once and as long as the force is present. Meaning, if a ball that is rolling experiences a wind force of 5N the ball's movement will increase 2 mph for example... as long as the wind force is present. Why is it that by gravity the falling object keeps on accelerating every second 9.8m/s. Why doesn't it just accelerate once 9.8 and that's it, until reaching terminal velocity?
 
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How is it that by a falling object if the object doesn't reach terminal velocity, it always falls with acceleration of 9.8m/s. It doesn't matter if the object has a gravity of 5N and air resistance of 4N or if the object has a gravity of 5N and air resistance of 1N... Why doesn't air resistance make a difference as to how much the object will accelerate?
 
BRH said:
I know that there is constant acceleration due to gravity. A regular force that is applied to a moving object causes the object to accelerate once and as long as the force is present. Meaning, if a ball that is rolling experiences a wind force of 5N the ball's movement will increase 2 mph for example... as long as the wind force is present. Why is it that by gravity the falling object keeps on accelerating every second 9.8m/s. Why doesn't it just accelerate once 9.8 and that's it, until reaching terminal velocity?
BRH said:
How is it that by a falling object if the object doesn't reach terminal velocity, it always falls with acceleration of 9.8m/s. It doesn't matter if the object has a gravity of 5N and air resistance of 4N or if the object has a gravity of 5N and air resistance of 1N... Why doesn't air resistance make a difference as to how much the object will accelerate?
Welcome to the PF.

Air resistance does affect the total acceleration of falling objects in an atmosphere. It is a retarding force, The sum of the two forces (gravity down and air resistance up) gives the total force and thus the total acceleration by Newton's Law:

ΣF = ma

:smile:
 
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BRH said:
How is it that by a falling object if the object doesn't reach terminal velocity, it always falls with acceleration of 9.8m/s. It doesn't matter if the object has a gravity of 5N and air resistance of 4N or if the object has a gravity of 5N and air resistance of 1N... Why doesn't air resistance make a difference as to how much the object will accelerate?

berkeman said:
Air resistance does affect the total acceleration of falling objects in an atmosphere. It is a retarding force, The sum of the two forces (gravity down and air resistance up) gives the total force and thus the total acceleration by Newton's Law:

... and when the 2 forces are equal ... the upwards force of the air resistance Vs the downwards force of gravity ...
then the total force = 0 (zero) and with zero force, there is zero acceleration and hence a terminal (fixed ) velocity
Dave
 
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