Answer:
1. Inertia is the property of an object that resists changes in its state of motion. An object with more mass has more inertia, meaning it is harder to change its motion. For example, a heavy truck has more inertia than a small car, so it takes more force to get the truck moving or to change its direction of motion.
2. Balanced forces are forces that act on an object in opposite directions and are equal in magnitude, resulting in no net force on the object. This means that the object will not accelerate or change its state of motion. Action-reaction forces, also known as Newton's Third Law forces, are forces that act on two objects in response to each other. These forces are always equal in magnitude and opposite in direction, but they do not cancel each other out because they act on different objects. An example of action-reaction forces is the force of a person pushing against the ground and the force of the ground pushing back against the person. While these forces are equal and opposite, they do not cancel out because they act on different objects.