Where r is the vector and the first derivative of time is the velocity (including magnitude and direction): dr/dt=-awsinwti+bwcoswtj. Take the first derivative of time, that is, R takes the second derivative of acceleration (including magnitude and direction) and time: -aw 2coswti-bw 2sinwtj (w 2 stands for the square of W). The resultant force is m times the acceleration. Then the force is (including magnitude and direction): m (-aw 2costi-bw 2sintj). Then it can be seen that the force is always opposite to the r direction (the ratio of I and J components is the same, both atgwt/b). Or further, the force vector divided by the r vector is -w 2. This is a negative number. When two vectors are divided into a pure negative number, it means that they are parallel and in opposite directions. R always starts from the original center outward, so the resultant force of particles always points to the origin.