What kind of motion is a uniform acceleration curve motion, a uniform deceleration curve motion

Uniform speed curve motion refers to the acceleration during the motion.

Motion in which the direction is different from the velocity and the acceleration is constant (i.e., the magnitude of the acceleration is constant, and the direction is also constant).

Definition. In the process of motion, the direction of acceleration is different from the direction of velocity and the acceleration is constant (i.e., the magnitude of acceleration does not change, and the direction does not change), such as flat throwing motion.

Displacement in the direction of muzzle velocity s=vot [no acceleration in the horizontal direction] displacement in the direction of acceleration h=1 2at 2 [no initial velocity in the vertical direction, i.e. vo=0] final velocity vt = gt on the vertical displacement

Note: Uniform variable speed circular motion.

The direction of acceleration changes, and the non-uniform speed curve moves. ）

, uniform acceleration movement, and uniform deceleration movement, there is no rigid, layer of unchanged difference;

The uniform acceleration curve movement in the east direction is the uniform deceleration curve movement in the direction;

Generally speaking, a, the oblique upward throwing motion, before reaching the highest point, is a uniform deceleration curve movement.

The premise of this statement is that the upward velocity is in the positive direction.

b. The oblique upward throwing motion, after reaching the highest point, is a uniform acceleration curve motion.

The premise of this statement is that the downward velocity is in the positive direction.

Through the above examples, it shows that when we make judgments, we actually have them in mind.

Reference direction. A is the reference direction in the upward direction, and in the downward in the B is the reference direction.

First: the curve moves, so the resultant force and the speed are not in the same straight line;

Second: uniform deceleration, indicating that the magnitude and direction of the acceleration of the wax return are unchanged, and the resultant force is unchanged.

Typical motion model guessing type: oblique upward throwing motion.

1.A curvilinear motion with constant "acceleration" is a "uniform" curvilinear motion.

For example, the acceleration of the "flat throwing motion" is unchanged (g = the magnitude and direction are unchanged), which is the motion of a uniform variable speed curve.

2.The curvilinear motion that the "acceleration" changes is the "variable acceleration" curvilinear motion.

For example, the acceleration change (direction change at all times) of "uniform circular motion" is a variable acceleration curve motion.

When a point is moving in a curve, "uniform speed motion" refers to () constant vector constant constant vector constant. Answer. b

1) Uniform variable speed curve motion refers to the motion in which the direction of acceleration is different from the direction of velocity and the acceleration is constant (that is, the magnitude of acceleration remains unchanged and the direction does not change) in the process of motion, such as flat throwing motion.

2) Definition: In the process of motion, the direction of acceleration is different from the direction of velocity and the acceleration is constant (that is, the magnitude of acceleration does not change, and the direction does not change), such as flat throwing motion.

Displacement in the muzzle velocity direction s=vot [no acceleration in the horizontal direction].

Displacement in the direction of acceleration h=1 2at 2 [no initial velocity in the vertical direction, i.e. vo=0].

The final velocity on the vertical displacement vt=gt

Note: Uniform speed circular motion acceleration direction changes, non-uniform speed curve movement. ）

Uniform speed curve motion formation conditions:

1.There is a certain initial velocity;

2.The acceleration is constant and the direction of acceleration is not in the same straight line as the direction of the initial velocity, otherwise it is a linear motion with uniform variable speed.

Uniform speed curve motion trajectory:

The resultant external force on the object is constant, and if the resultant external force (or acceleration) is perpendicular to the initial velocity, it is a common parabola, and the trajectory equation is in the form y=ax 2.

If the resultant external force (or acceleration) is at an angle to the initial velocity, the curve will be more complex, but it is still parabolic, and the trajectory equation is in the form of y=ax 2+bx.

Uniform variable speed curve motion refers to the movement in which the direction of acceleration is different from the direction of velocity and the acceleration is constant (i.e., the acceleration is large and the empty mode is small, and the direction is also unchanged) in the process of motion.

For example, the flat throwing motion, although it is a curve such as a slow motion, but the force is always only gravity, so the acceleration is always only gravitational acceleration, which has always been unchanged. So it's a uniform speed curve movement.

In the case of uniform circular motion, although the magnitude of velocity and acceleration remain unchanged during the motion, the direction of acceleration has been changing, so the acceleration has been changing. Therefore, it is not a uniform variable speed curve motion.

Definition. When the external force on the object is constant and not in the same straight line as the direction of velocity, the object moves in a uniform variable speed curve. Such as (class) flat throwing motion, (class) oblique throwing motion.

Displacement in the muzzle velocity direction s=vot [no acceleration in the horizontal direction].

Displacement in the direction of acceleration h=1 2at 2 [no initial velocity in the vertical direction, i.e. vo=0].

The final velocity on the vertical displacement vt=gt

Note: The circular motion of uniform speed accelerates the change of the direction of the collision, and the non-uniform speed curve moves. ）

Formation conditions. 1.There is a certain initial velocity;

2.The acceleration is constant and the direction of acceleration is not in the same line as the direction of initial velocity.

Locus. The resultant external force on the object is constant, and if the resultant external force (or acceleration) is perpendicular to the initial velocity, it is a common parabola, and the trajectory equation is in the form y=ax 2.

If the resultant external force (or acceleration) is at an angle to the initial velocity, the curve will be more complex, but it is still parabolic, and the trajectory equation is in the form of y=ax 2+bx.

Conclusion. When we learn the knowledge of linear motion with uniform variable speed, we often use the conclusion that the average velocity of an object moving in a linear motion with uniform variable speed in time t is equal to the instantaneous velocity of the object at the middle moment of this time, that is, (the proof process is omitted).

So, is this conclusion also applicable in the motion of a uniform speed curve? Of course, we can orthogonally decompose a curved motion with uniform velocity into 2 linear motions with uniform speed. The linear motion of the uniform velocity in these two directions is used separately to find the velocity at the intermediate moment and the average velocity of this curved motion, and You Xiaoxiao compares their magnitude and direction and draws a positive conclusion.

Analysis: This is not necessarily.

For example, when moving in a uniform circular motion, the acceleration and velocity are always perpendicular, so the velocity only changes in direction, and the velocity does not change in magnitude, and changes uniformly.

For example, flat throwing motion, a typical curvilinear motion, in which, the direction of acceleration is always vertical downward, then, the speed is changing all the time, and not only the direction is changing, but also the magnitude, and the analysis shows that the change is uneven. If you compare the horizontal and vertical directions separately, then they are uniformly varied, but once the combined velocity and acceleration are considered, then they are not uniform.

To sum up, it is wrong to say that the velocity of a certain curvilinear motion with acceleration varies evenly.

Not necessarily.

For example, an object that is thrown out moves in a curve in the air and is only affected by gravity, and the acceleration is the acceleration of gravity, which remains the same!!

However, the speed at which the object moves in a curve must change!

Because the direction of the speed of the curve is changing all the time.

To be precise, it is a uniform deceleration motion, and the reverse uniform acceleration motion means that the acceleration direction is opposite to the velocity direction, and the acceleration is uniform, that is, constant! This is another expression of uniform deceleration motion.

However, a reverse uniform acceleration motion is also a uniform acceleration motion (a motion with constant acceleration)! Note - "Uniform acceleration motion" is defined from the perspective of acceleration, which is generalized, and includes the motion of acceleration and velocity in the same direction, as well as the motion of acceleration and velocity in the opposite direction; It's completely different from "accelerated motion" (defined in terms of speed)!

So – both statements are true, but the latter is more accurate! is the best answer! This question is the same as asking a man "Are you a human being, or a man?" "It's the same thing!