explain why we never see objects continuing to move in a straight line indefinitely, despite their inertia.

Inertia is a property of matter that causes it to resist changes in its state of motion. According to Newton's first law of motion, an object in motion will stay in motion, moving in a straight line, unless acted upon by an external force. This is the principle of inertia.

However, in our everyday experience, we never see objects continuing to move in a straight line indefinitely. This is because there are always forces acting upon objects. Here are the steps explaining why:

1. Friction: When an object is moving on a surface, there is always a force of friction acting against the direction of motion. This force gradually slows down the object and eventually brings it to a stop.

2. Air Resistance: Even if an object is moving in the air, there is still a force acting against it, which is air resistance. This force also slows down the object and eventually stops it.

3. Gravity: Gravity is a force that pulls objects towards the center of the Earth. If an object is moving horizontally, gravity will eventually cause it to move in a downward direction.

4. Interactions with Other Objects: If an object collides with another object, the force of the collision will change the object's direction of motion.

So, even though an object has inertia, there are always forces acting upon it that prevent it from moving in a straight line indefinitely.