Inertia is the tendency of an object to resist changes in its motion. Therefore, any force that causes a change in an object's motion works against inertia. Here are two examples:

1. Applied Force: This is any force directly applied to an object, like pushing a box or pulling a rope. This force directly changes the object's velocity, overcoming its inertia.

2. Friction: This force opposes motion between two surfaces in contact. When you push a box across the floor, friction slows it down, working against the inertia that wants the box to keep moving at a constant velocity.

Let me know if you'd like more examples or want to explore the concept of inertia further!