Final answer:
To find the times at which a particle stops, we need to analyze the forces acting on the particle and identify when the net force is zero.
Step-by-step explanation:
The question is asking for times at which a particle stops. In order to find these times, we need to consider the forces acting on the particle. When a particle comes to a stop, it means that the net force acting on it is zero. This can occur when the force of friction is equal to the applied force or when the particle encounters a stopping mechanism such as a wall or a spring. By analyzing the forces and their effects, we can identify the times at which the particle stops.