Newton's First Law of Motion is Wrong (Proven Wrong in This Thread)

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Discussion Overview

The discussion centers around the validity of Newton's First Law of Motion, particularly in the context of an experiment involving two balls colliding on a frictionless plane. Participants explore the implications of the collision on the law and challenge each other's interpretations of force and acceleration during the event.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant argues that the collision of two balls moving at constant velocity demonstrates that an object does not necessarily remain in motion at a constant velocity, as they come to rest after colliding.
  • Another participant counters that during the collision, the balls exert forces on each other, which contradicts the claim that no external force is acting.
  • Some participants emphasize that the acceleration of the balls is zero before the collision, leading to the conclusion that no force is produced until the collision occurs.
  • Others point out that once the balls collide, they experience non-zero acceleration, which implies the presence of a force acting on them.
  • One participant expresses frustration at the misunderstanding of the theory, suggesting that the original claim fails to recognize the forces at play during the collision.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the interpretation of Newton's First Law and the role of forces during the collision.

Contextual Notes

There are unresolved assumptions regarding the definitions of force and acceleration in the context of collisions, as well as the implications of inelastic collisions on the application of Newton's laws.

NewtonWasWrong
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Please note this is a very serious thread.

Please note Newton's First Law:

First law: When viewed in an inertial reference frame, an object either remains at rest or moves at a constant velocity, unless acted upon by an external force.


Here is an experiment to prove this First Law wrong.
Consider two balls rolling at a constant velocity directly toward each other on a frictionless plane. Ball A is heading due east at 5 m/s and Ball B is heading due west at 5 m/s. The balls engage in an inelastic collision. The balls will both come to rest. This can be proven experimentally.

Please note that Newton's Second Law describes Force = Mass * Acceleration. Neither ball has an acceleration, meaning that neither ball has any force associated with it. So despite not being acted upon by any FORCE, during the collision, the balls change velocity from 5 meters/second to zero. This simple experiment clearly shows that an object will not necessarily stay in motion at a constant velocity despite not being acted upon by an external force.
 
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NewtonWasWrong said:
Please note that Newton's Second Law describes Force = Mass * Acceleration. Neither ball has an acceleration, meaning that neither ball has any force associated with it. So despite not being acted upon by any FORCE, during the collision, the balls change velocity from 5 meters/second to zero. This simple experiment clearly shows that an object will not necessarily stay in motion at a constant velocity despite not being acted upon by an external force.
This is silly. When the balls collide they exert forces on each other!
 
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Doc Al said:
This is silly. When the balls collide they exert forces on each other!
Please note Newton's Second Law of Motion:

Second law: The vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object; thus, F = ma.

Please note that the acceleration of both balls are equal to 0. Please note that mass*0=0. Consequently, neither ball produces a force (or rather, produces a force equal to 0).
 
NewtonWasWrong said:
Please note that the acceleration of both balls are equal to 0.
Only before they collide! Once they collide, they certainly have a non-zero acceleration. You indicated such yourself!
 
NewtonWasWrong said:
Please note Newton's Second Law of Motion:

Second law: The vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object; thus, F = ma.

Please note that the acceleration of both balls are equal to 0. Please note that mass*0=0. Consequently, neither ball produces a force (or rather, produces a force equal to 0).

In the collision, both balls change their speed from five meters/second to zero meters per second. That's an acceleration, and you can even calculate its average value throughout the collision: If the time between when the balls first touch andwhen they stop moving is ##\Delta{t}## seconds, the average magnitude of the acceleration will be ##\frac{\Delta{v}}{\Delta{t}} = \frac{5}{\Delta{t}} m/sec^2##.

Non-zero ##a##, non-zero ##m##, got to be a non-zero ##F##.
 
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NewtonWasWrong said:
Please note this is a very serious thread.
Next time, before posting an obviously wrong and completely ignorant challenge to an established theory it might be good to exercise a little humility and actually learn enough of the theory to be able to use it correctly.

You completely failed to recognize the obvious forces acting on the objects, and therefore completely failed to correctly apply the theory. Furthermore, you arrogantly assumed that you were the only person in the last 300 years smart enough to have correctly analyzed an inelastic collision using the theory.
 
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