Describe the movement of an object

The relationship between object motion and object interaction

The problem of equilibrium of objects under interaction

P coordinate (x, y, z)

Vector diameter size

sagittal direction

vector analogy to higher numbers

1. s scalar

2. Generally, it is not equal to r.

3. When the particle moves in a straight line in one direction or t approaches zero, s and r will be equal.

Expression

The first derivative of the position vector with respect to time at this moment

size:rate

Direction: The limit direction of 🔼r when t is close to zero