Final answer:
Gravitational force is not taken into account when analyzing torque and angular momentum because it usually has a negligible effect on most systems.
Step-by-step explanation:
The reason we don't take gravitational force into account when analyzing torque and angular momentum is because it produces a negligible effect on most systems. While gravitational force can produce torque and change the angular momentum of a system, its effect is usually very small compared to other forces acting on the system. For example, when considering the motion of objects on Earth's surface, the gravitational force is much weaker compared to frictional forces and other external torques.