Is the direction of the resultant force the direction of acceleration?

In the classical mechanics category, in an inertial frame, the direction of the resultant force is the direction of acceleration f=ma

In high school, you may wish to think that the two directions are the same.

On the other hand, of course, we perceive the presence of force through acceleration (deformation can be seen as the result of acceleration produced by molecules). The so-called force is nothing but an explanation of acceleration.

Yes, Newton's second law knows that the direction of acceleration coincides with the direction of the resultant force experienced.

is the direction of the resultant acceleration.

Yes The direction of both is consistent at any time.

In classical mechanics (Newtonian mechanics), f=ma, f, and a are all vectors, which represent the magnitude and direction, and f is the resultant force, from which it can be seen that the direction of the resultant force is the same as the direction of the resultant acceleration.

It is important to note that Newtonian mechanics only applies to objects moving at low and macroscopic speeds, and does not apply to microscopic or high-speed (orders of magnitude close to the speed of light).

From the perspective of Einstein's theory of relativity, since f=dp dt=d(mv) dt, and the mass m is related to the velocity v, and a=dv dt, so f=m*dv dt+v*dm dt=ma+v*dm dt, at this time, the vector is still true, it can be seen that in f there is not only the component ma of acceleration about a, but also the v*dm dt component, and the direction of this component (i.e., the direction of velocity v) is often different from the direction of acceleration, therefore, from the perspective of relativity, The direction of the resultant force is different from the direction of the resultant acceleration.

However, for the low-speed motion state, m is approximately equal to the static mass m0, that is, the v*dm dt component is approximately equal to zero, and the direction of the resultant force can be approximated to be consistent with the direction of the resultant acceleration.

The direction of the resultant force on an object moving in a curvilinear motion is not only at an angle to the direction of its velocity, but always points to the "inside" of the curve.

In curvilinear motion, the instantaneous velocity direction is along the tangent direction of the point, or the velocity is always tangent to the path at any moment; Moreover, the trajectory is always deviated in the direction of the resultant force, in other words, that is, the angle between the direction of velocity and force must include its trajectory path. Some students summarized it as:

The force speed clamp path, the speed diameter is always tangent.

If the two forces are not collinear, the direction of the diagonal is the direction of the resultant force.

If the direction of the two forces is the same, then the resultant force is equal to the sum of the two forces and the direction does not change.

If the direction of the two forces is opposite, then the resultant force is equal to the difference between the two forces in the same direction as the direction of the larger force.

If the two forces are equilibrium forces (equilibrium forces of equal magnitude and opposite directions), the resultant force is zero. ∑f=0

1. In classical mechanics, f and a are both vectors, which represent both magnitude and direction, and f is the resultant force, from which it can be seen that the direction of the resultant force is consistent with the direction of the resultant acceleration;

2. However, it should be noted that Newtonian mechanics is only applicable to macroscopic and low-speed moving objects, and is not valid for microscopic or high-speed situations;

3. The acceleration slag rise is the ratio of the velocity change to the time taken for this change to occur, and it is the physical comma of the speed change of the object, which is usually expressed by a;

4. Acceleration is a vector quantity, and its direction is the direction of the change in the velocity of the object, which is the same as the direction of the resultant external force;

5. Definition of resultant force: If the effect produced by one force is the same as that produced by two forces, this force is called the resultant force of the two forces.

The direction of the acceleration code is hidden: the same direction as the velocity change v. The direction is the same as the resultant external force.

When the direction of acceleration is the same as the direction of velocity, 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.

That is: acceleration motion: v>0, ɑ>0 or v<0, ɑ<0 deceleration motion:

v>0,ɑ<0 or v>0,ɑ<0 acceleration is the ratio between the amount of velocity change and the time used for this change to occur δv δt, which is a physical quantity that describes the speed change of an object, usually expressed by a and in m s2.