Name the force which always opposes motion.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the force that always opposes motion.

2. **Identifying the Force**: In physics, there is a specific force known for opposing motion. This force is called the "friction force."

3. **Explanation of Friction Force**: The friction force acts between two surfaces in contact. When an object is in motion or when an attempt is made to move it, the friction force acts in the opposite direction to the applied force.

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