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

• NewtonWasWrong
In summary, Newton's First Law states that an object will remain at rest or in motion at a constant velocity unless acted upon by an external force. However, an experiment with two balls rolling at a constant velocity towards each other and engaging in an inelastic collision proves this law wrong. This is because Newton's Second Law of Motion states that the vector sum of the forces on an object is equal to its mass multiplied by its acceleration. Despite initially having no acceleration, the balls change velocity during the collision, indicating that there must have been forces acting on them. This experiment demonstrates that an object may not stay in motion at a constant velocity even without an external force acting upon it. Additionally, the person challenging the law failed to correctly apply the theory
NewtonWasWrong
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.

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!

russ_watters
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##.

1 person
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.

russ_watters, Vanadium 50, vanhees71 and 3 others

## 1. Is Newton's First Law of Motion really wrong?

No, Newton's First Law of Motion is not wrong. It has been proven through countless experiments and observations and is considered a fundamental principle in classical mechanics.

## 2. What is Newton's First Law of Motion?

Newton's First Law of Motion states that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an external force.

## 3. What evidence proves that Newton's First Law of Motion is wrong?

There is no evidence that proves Newton's First Law of Motion is wrong. The law has been repeatedly confirmed through experiments and observations, and there is no scientific evidence to suggest otherwise.

## 4. Who disproved Newton's First Law of Motion?

No one has been able to disprove Newton's First Law of Motion. It is a well-established principle in physics and has been confirmed by numerous scientists and experiments.

## 5. Why do some people believe that Newton's First Law of Motion is wrong?

Some people may mistakenly believe that Newton's First Law of Motion is wrong because they may have seen instances where an object appears to be at rest but is actually in motion, such as a ball rolling down a hill. However, this is simply a misunderstanding of the law and does not disprove it.

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