How does an object maintain constant velocity according to Newton's First Law?

In summary: It could of course be that the object was formed out of matter which already has momentum - like the solar system,However the momentum in that case hasn't come from nothing, it's momentum that was previously included in a nebula, and now is included in the Sun.In relation to the original question," How is the object begin moving , Is net force applied initially before it reaches its constant velocity?",It is correct to say that a force must have been applied to the object in order for it to move. However, it is not correct to say that the object "doesn't have to begin moving". Every object always moves in some inertial frames, and Newton's first law applies in all of them.
  • #1
Musica
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Newton's first law says that when an object is at rest or moving in constant velocity, it will stay that way unless external force is applied. So, net force is zero.

What I don't get is on an object moving in constant velocity. How is the object begin moving? Is netforce applied initially before it reaches its constant velocity?
 
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  • #2
Musica said:
Newton's first law says that when an object is at rest or moving in constant velocity, it will stay that way unless external force is applied. So, net force is zero.

What I don't get is on an object moving in constant velocity. How is the object begin moving? Is netforce applied initially before it reaches its constant velocity?
How it got that way is not part of the first law of motion, but yes, to get something moving on, for example, a flat surface, you have to give it a push. If the surface is frictionless it just keeps moving. If you don't give it a push it just keeps sitting there.
 
  • #3
Musica said:
How is the object begin moving?
The object itself doesn’t have to begin to do anything. You can analyze any object in a reference frame where it always has been moving.
 
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  • #4
Consider a frictionless surface.
 
  • #5
Musica said:
Is netforce applied initially before it reaches its constant velocity?
Yes, some force must have been applied to the object in it's past in order to accelerate it to the velocity which it presently has.
(In relation to the same given frame of reference)
 
  • #6
Before Newton, people didn't know or realize that things could move on their own. He taught people that if something gets a push in one direction, it will need a push is the opposite direction to stop.
 
  • #7
rootone said:
Yes, some force must have been applied to the object in it's past in order to accelerate it to the velocity which it presently has.
(In relation to the same given frame of reference)
Why would one assume that in the infinite past that the object was at rest in an arbitrarily selected frame of reference?
 
  • #8
jbriggs444 said:
Why would one assume that in the infinite past that the object was at rest in an arbitrarily selected frame of reference?
Because it's unlikely that the moving object does have an infinite past.
It could of course be that the object was formed out of matter which already has momentum - like the solar system,
However the momentum in that case hasn't come from nothing, it's momentum that was previously included in a nebula, and now is included in the Sun.
 
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  • #9
rootone said:
It could of course be that the object was formed out of matter which already has momentum
What do you mean by "it could be"?. It is absolutely certain that there are inertial frames (infinitely many) where it always had momentum.
 
  • #10
Poor wording on my part, yes I agree there certainly are frames where an object always had momentum,
In relation to the original question," How is the object begin moving , Is net force applied initially before it reaches its constant velocity?",
I was trying to explain that if the object was motionless at one stage and now it isn't, then a force must have been applied to it.
On the hand an object which comes into existence in an already moving condition, and still is moving now, doesn't 'begin to move' and no force need have been applied to it since it started existing.
 
  • #11
rootone said:
In relation to the original question," How is the object begin moving , Is net force applied initially before it reaches its constant velocity?",
The correct answer to that question is, that the object doesn't have to begin moving. It is always moving in some inertial frames and Newtons 1st Law applies in all of them.
 
  • #12
Blackberg said:
Before Newton, people didn't know or realize that things could move on their own. He taught people that if something gets a push in one direction, it will need a push is the opposite direction to stop.
And rightly so, most objects on Earth stop moveing because of friction they don't need a push in the opposite direction to make them stop.Newton was probably referring to celestial bodies which would be a hard concept to grasp let alone explain at that time.
 

FAQ: How does an object maintain constant velocity according to Newton's First Law?

What is Newton's First Law of Motion?

Newton's First Law of Motion states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

What is the significance of Newton's First Law of Motion?

Newton's First Law of Motion is also known as the Law of Inertia and it is important because it explains the concept of inertia and how objects tend to resist changes in their state of motion.

How does Newton's First Law of Motion apply to everyday life?

Newton's First Law of Motion can be observed in everyday life, such as when a car comes to a stop, the passengers continue to move forward due to their inertia. It also explains why objects tend to stay in motion, such as a rolling ball will continue to roll unless acted upon by an external force.

What is the difference between Newton's First Law of Motion and the Law of Inertia?

Newton's First Law of Motion and the Law of Inertia are essentially the same concept, but the Law of Inertia refers specifically to the tendency of objects to resist changes in their state of motion, while Newton's First Law of Motion explains this concept in the broader context of forces and motion.

How did Newton come up with the First Law of Motion?

Newton's First Law of Motion was first described in his book "Philosophiæ Naturalis Principia Mathematica" in 1687. He based his law on the work of previous scientists, such as Galileo, who also studied the concept of inertia.

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