How to see the positive and negative velocity on the image of simple harmonic vibration

The direction of acceleration always points to the equilibrium position and always points to the abscissa on the vibration image. The direction of speed is the direction of the actual movement of the object. Judging from the position of the object at the next moment, if the object is in the positive X direction at the next moment, then the object is moving in the positive X direction, and the speed direction is the positive X direction. or vice versa, Dallas to the auditorium

The images of acceleration and time need to define the initial velocity. The initial speed plus the area between the image and the time axis (the upper area is positive and the lower area is negative) is the speed. Look at the pros and cons of this.

Extended data:

When the deflection angle is small, we can approximate it as the red arrow in the figure, that is, the displacement X (restoring force) is perpendicular to the equilibrium position.

The derivation of displacement uses the knowledge of trigonometric function (Ω t+φ), that is, the angle, and uses trigonometric function to get the distance between point O and the end position, that is, the displacement. (the displacement is negative, that is, the left direction is set to the positive direction), so the equation x=Rcos(ωt+φ) is obtained.

The swing of a simple pendulum near the equilibrium position (within a small angle range) not only makes a circular motion, but also makes a simple harmonic vibration. The resultant force of all forces on the pendulum ball should provide its centripetal force for circular motion.