How to determine the direction of the velocity, how to judge the direction of the velocity

Looking at the direction of the force, the resultant force is found by vector graphing, and the direction of the resultant force is the direction of acceleration.

Generally, objects on a horizontal plane (such as placed on a tabletop, in mid-air, against a wall, etc.), choose the Cartesian coordinate direction, that is, all the forces are divided into horizontal and vertical directions, cancel each other out and see the resultant force.

For objects in the inclined plane (such as on the slope), the inclined plane is the x-axis, and the perpendicular one is the y-axis, and the gravity is generally decomposed, and the two forces decomposed are partly offset by the support force perpendicular to the inclined plane, and partly offset the frictional force with the inclined plane.

In other cases, you can use whichever side is more convenient, there is no absolute limit.

Upstairs, I saw the wrong thing, people asked about the velocity, not the acceleration. What is the direction of velocity without excessive? It seems that this minute velocity is artificially prescribed, and I forgot what high school physics says.

It seems that the problem that comes up often is the motion of an object, and then find the horizontal and vertical velocity and solve it with the square relation.

In any case, the actual direction of velocity must be determined, and there is only one, and in order to facilitate the study of the problem, it may be found that the partial velocity in a certain direction may be obtained, but this direction can be arbitrarily prescribed, all for the convenience of disintegration.

The curve of curvilinear motion refers to the trajectory of motion, which is a line formed by the position of the particle at each moment, and each point above represents the position of the particle at a certain moment

1.In linear motion, the "direction of velocity" is the "direction of motion" of the object

2.Movement in curves.

, the "velocity direction" is along the tangent of the object's high motion.

direction".3.The change in the direction of the velocity is at the moment of "the velocity is zero".

The direction of angular velocity is perpendicular to the circular face of the object's motion and is always perpendicular to the direction of velocity, and the direction obeys the right-hand spiral law. So the angular velocity direction is generally constant.

The direction of angular velocity obeys the right-hand spiral. That is, the direction of the four fingers of the right hand is the same as the direction of movement, the thumb is vertically eliminated, and the direction of the thumb is the direction of angular velocity.

Thus, it is clear that the angular velocity of an object moving in a circle within the plane will only go up or down, perpendicular to the plane.

The direction of velocity is the tangent direction of the curve. Calculation formula:

1. V (linear velocity) = δs δt = 2 r t = r = 2 rn (s represents arc length, t represents time, r represents radius, n represents rotational speed).

2. (angular velocity) = δt = 2 t = 2 n ( indicates angular knowledge of the degree of trouble or radian).

3. t(period) = 2 r v = 2 1 n.

4. n** speed) = 1 t = v 2 r = 2 .

(1) In physics, velocity is a vector quantity, which has both magnitude and direction. The direction of velocity is the direction in which the object is actually moving (or moving).

2) Difference from the direction of acceleration: The direction of acceleration is not necessarily the same as the direction of motion, but it is the same as the direction of the resultant force experienced by the object.

The relationship between the direction of velocity and the direction of acceleration is: when the acceleration and velocity direction are the same, the object moves at an accelerated pace; When the direction of acceleration is opposite to the direction of velocity, the object moves in a deceleration motion.

Understanding of Newton's Second Law:

1. Modeling.

Newton's second law can only be studied by a particle model or an object that can be seen as a particle model.

2. Causality.

Force is the cause of acceleration, mass is a measure of the magnitude of an object's inertia, and the acceleration of an object is the result of the combined action of the external cause of force and the internal cause of mass.

3. Vectorality.

The direction of the resultant external force determines the direction of acceleration, the direction of the resultant external force changes, the direction of acceleration changes, and the direction of acceleration is consistent with the direction of the resultant external force. In fact, Newton's second law is expressed in the form of vectors.

4. Transientness.

Acceleration and the resultant external force are instantaneous correspondences, and they are born together, die together, and change together.

In short, it is the direction of the object's motion The velocity v direction is the same as the direction of motion, but the acceleration a direction is not necessarily.

The direction of motion of an object, the direction of the line from the beginning to the end of an object, which is the direction of the line from the beginning to the end point.

Velocity is a vector, but there is a positive and negative ......So there is forward or backward .........That's probably it.

The determination of the direction of velocity is based on the trajectory of the particle, at a certain point on the trajectory, the tangent tremor wheel that crosses this point to make the trajectory curve rough, and the direction of the tangent is the direction of velocity. Of course. This question also tests students' understanding of the relationship between force and curvilinear motion.

First, look at the direction of the electric field force at a certain point on the trajectory, and then according to the direction of the centripetal force of the particles on the curve, if the angle between the direction of the electric field force and the direction of the centripetal force is less than 90 degrees, then the lead trace of this motion rail is possible; If it is greater than or equal to 90 degrees, it is not possible to use this trajectory.

I choose AD for this question

First: "Does inertia give it a force to the right horizontally" - false. Inertia is only determined by the mass of the object (mass is a measure of the magnitude of inertia), large inertia only characterizes the mass of the object, and small inertia only characterizes the small mass of the object; The "force" is the action of the object on the object, and your question is completely "why doesn't the inertia of the plane give it a horizontal force" - this is equivalent to saying "why the mass of the plane not".

This is obviously absurd, because the mass of an object is not the same as whether it has any force on another object. Therefore, after the object is released, because it is only affected by gravity, its acceleration is the gravitational acceleration straight downward.

Second, the direction of velocity, for curvilinear motion (here the object does a flat motion after leaving the plane, and the trajectory is parabolic), the velocity follows the tangent direction on the curve, so the direction of velocity changes all the time.

For the concepts of physics in high school, it is a bit difficult to understand at first, but believe me, physics is probably the most interesting course - those who are not interested in physics are difficult to understand or unwilling to think deeply or the teacher himself is confused. I believe that after the start of school, you will enjoy this course and will definitely be able to learn well.

The velocity is the original object just out of the plane, and it has not begun to be affected by gravity, so the direction of speed is the same as that of the plane, and the size is the same as the plane. The fall of an object is only affected by gravity, so the acceleration of the object is downward in the direction of gravity, inertia is not a force, and there is no action of force. When an object falls, there will be a downward velocity due to gravity...

It turns out that it is horizontal to the right, and the combined speed is to the right corner!!

Inertia does not give it a force to the right horizontally.

The direction of its acceleration is perpendicular downward, i.e., the direction of the resultant force, and here only the gravitational force f=ma

As for the direction of its velocity: is the direction of the vector sum of horizontal velocity and vertical velocity.