Torque is a measure of the twisting force that tends to cause rotation. It is the product of the force applied to an object and the distance from the point of rotation to the point where the force is applied. Mathematically, torque (τ) is calculated as τ = r x F, where r is the vector representing the distance from the point of rotation to the point where the force is applied, and F is the force vector.

In the context of center of mass and system of particles, torque can be used to analyze the rotational motion of a system. When multiple particles are involved, each particle exerts a torque on the system based on its mass, distance from the axis of rotation, and the force acting on it. The net torque on the system is the sum of all the individual torques.

Numerical problems related to center of mass and system of particles may involve calculating the torque exerted by different particles, finding the net torque on the system, or determining the conditions for rotational equilibrium. These problems often require understanding the principles of torque and the properties of the system being analyzed.