Question on Newton's first law

In summary, an object with no resultant force can still be moving at constant velocity due to Newton's First Law of Motion. This law states that an object in motion will continue to move without change in its motion unless acted upon by a net force. While common sense may suggest a constant force is needed to maintain motion, this is not the case as friction and air resistance can obscure underlying laws. The object's momentum and kinetic energy are also affected by changes in speed, which require a force.
  • #1
Lim Y K
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An object with no resultant force can still be moving at constant velocity. Why? Is it because of its kinetic energy or has it got nothing to do with energy?
 
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  • #2
Lim Y K said:
An object with no resultant force can still be moving at constant velocity. Why? Is it because of its kinetic energy or has it got nothing to do with energy?
An object which is moving which also has no net force acting on it continues to move without change in its motion. That's Newton's First Law of Motion.

If you want to make an object go slower, you must apply some force to it.
If you want to make an object go faster, you must apply some force to it.
If you want the motion of the object to stay the same, don't apply any force to it.

Newton's First Law is not concerned with how the motion of the object started initially, only what happens to the object while it is in motion (or not, as the case may be).
 
  • #3
Lim Y K said:
Is it because of its kinetic energy or has it got nothing to do with energy?

In addition to SteamKing's answer: It is because of its momentum but it has also to do with energy. Changing the speed changes momentum and kinetic energy and both require a force.
 
  • #4
Common sense and intuition can be deceptive. In everyday experience a constant force may seem to be needed to keep an object moving. However, Galileo discovered that friction and air resistance were obscuring underlying laws. Galileo is quoted verbatim in Newton's First Law.
 

1. What is Newton's first law?

Newton's first law, also known as the law of inertia, states that an object at rest will remain at rest and an object in motion will continue in motion with a constant velocity unless acted upon by an external force.

2. Who was Sir Isaac Newton?

Sir Isaac Newton was an English physicist and mathematician who is widely recognized as one of the most influential scientists in history. He is best known for his work in mechanics, including the formulation of his three laws of motion.

3. How does Newton's first law apply to everyday life?

Newton's first law can be observed in everyday life, such as when a book remains on a table unless someone picks it up or when a soccer ball continues to roll unless it is stopped by a force. It also explains why objects in space continue to move in a straight line unless acted upon by gravitational forces.

4. What is the difference between Newton's first law and the law of inertia?

Newtons's first law and the law of inertia are essentially the same thing. The term "inertia" refers to an object's resistance to changes in its state of motion, which is what Newton's first law describes.

5. Can Newton's first law be violated?

No, Newton's first law is a fundamental principle in physics and has been extensively tested and proven to be true. It is considered a universal law and applies to all objects in the universe.

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