If the state of motion of the object does not change, it must not be affected by external forces, fo

This is very simple, if an object is subjected to a force of 10N forward, and at the same time it is subjected to a force of 10N backward, and the net force is 0N, according to Newton's law, the state of motion does not change. For example, if a car moves in a straight line at a speed of 30m s, the power provided by the engine is 1000N, and all the resistance it receives is also 1000N, then its resultant force is f=0, f=mxa, so the acceleration is 0, the velocity is unchanged, and it still maintains the original linear motion state.

For example, if an object moves in a straight line at a uniform velocity, its state of motion does not change, but it is affected by gravity. Gravity is an external force. Force is not the cause of maintaining the physical state of motion, but the cause of changing the state of motion of the object

The force is the cause of the change in the motion of the object, but the fact that the motion of the object does not change does not mean that it does not accept the influence, for example, if a car moves in a uniform straight line on the road, he receives the friction of the ground and the traction of his own engine, but the two forces are equal in magnitude and opposite in the direction.

For example, you're running, and then someone behind you hits you with a stick, but you can still run.

It is not that it is not affected by external forces, but that the external forces are balanced, so it is not affected.

The following phenomena do not change the state of motion of the object.

It should be zero resultant force!!

Put it on the table late you don't touch it and it doesn't move.

That's right. The force on the object can be divided into several situations, such as the downstream force:

1.The object is subject to only one force, in which case the state of motion of the object must change;

2.The object is acted upon by several forces, which are divided into two cases: if the net force of the object is 0, the action of these forces cancels each other out, and the state of motion of the object does not change; If the net force exerted by the hail of the object is not zero, the action of these forces will not cancel each other out, and the state of motion of the object must change.

Newton's first law tells us that when an object is not subjected to any external force, it always remains at rest or in a state of linear motion at a uniform speed

So the answer is: static; Uniform linear motion

Force is the reason for changing the state of motion of an object, right, right, right, right

According to Newton's laws, force is what changes the state of motion of an object. In the absence of force, the object will move in a straight line at a uniform speed.

More than 2,000 years ago, the ancient Greek scholar Aristotle believed that force is the cause of maintaining the motion of objects, which seems to be very similar to what we know.

More than 400 years ago, Galileo Galilei proposed that force is not what sustains the motion of an object, but what changes it.

In 1644, Descartes further developed a new theory, which meant that if not acted on by force, an object would maintain a uniform linear motion.

In 1687, Newton published the famous "Mathematical Principles of Natural Philosophy", which formally proposed Newton's first law, which means that if there is no force to act, an object will always maintain a uniform linear motion or a state of rest.

Students who have gone to junior high school physics should not hesitate to shout that force is the reason for changing the state of motion of objects.

This is not only that we were born more than 400 years later than Galileo, but also because we have experienced a full 9 years of compulsory education, if there is no nine years of compulsory education, we rely on ourselves to cover our heads, even if we were born 400 years later, Hengzhi may still think that force is the reason for maintaining the movement of objects, after all, the knowledge in life is: I push you, you will move.

Now think about it very simply, force is the cause of changing the state of motion of an object, and the object remains in its original state when it is not acted on by force, either at rest or in a uniform linear motion.

Yes. If the motion of the object changes, then it must be affected by an external force.

Newton's first law, also known as the law of inertia and the law of inertness, states that any object must remain in a uniform linear motion or at rest until an external force forces it to change its state of motion. It shows that when the resultant external force is zero, the object that was originally at rest will continue to remain at rest, and the object that was originally moving will continue to move in a straight line at the original velocity.

The net external force is zero includes two situations: one is that all the external forces experienced by the object cancel each other out, and the net external force is zero; The other is that the object is not acted upon by an external force.

This theorem is demonstrated by Galileo's experiment with an ideal inclined plane: if the ball is rolled down from rest along a smooth inclined plane, the ball will roll up to another inclined plane, reach a height about the same as the original, and then roll down. It is inferred that it is only because of friction that the ball fails to reach its original height.

Then, reduce the inclination of the next inclined plane, and the ball still reaches the same height on this inclined plane, but at this time it.

Roll farther. Continue to reduce the inclination of the second bevel and the ball will roll farther when it reaches the same height.

So the situation was studied when the slope was laid flat, and it was clear that the ball would roll down forever. That is to say, the force is not the reason for maintaining the motion of the object, i.e., maintaining the speed of the object, but precisely the reason for changing the state of motion of the object, that is, changing the velocity of the object, once the object has a certain velocity, if it is not subjected to force, it will move in a straight line at this speed at a uniform speed.

A change in the motion of an object means a change in velocity.

When an object moves at a uniform speed, the velocity does not change, so the force does not change.

But if it is subjected to a resultant external force, the direction of the resultant force remains the same, and the acceleration it provides is constant, so the velocity will always increase or decrease. At this time, the velocity changes, the state of motion changes, but the resultant external force is constant.

The most obvious is the uniform circular motion, the velocity is always changing, but the resultant external force is always directed towards the center of the circle, so it can also be explained.

The following phenomena do not change the state of motion of the object.

The effects of force are: 1) changing the state of motion of the object, and 2) changing the shape of the object.

Therefore, when an object is subjected to force, it may change its state of motion, it may change the shape of the object, or it may change the state of motion and shape of the object at the same time. Therefore, "as soon as the object is subjected to a force, the state of motion must change". Such a statement is incorrect.

Too absolutely.

Some gravitational balance forces can cancel each other out.

So it's still the same.

Force can deform an object, and force can change the state of motion of an object.

Balanced and unbalanced? Well......