Understanding Friction When a Body Tends to Move

Friction is a force that opposes motion or the tendency of motion between two surfaces in contact. There are different types of friction, depending on the state of motion between the surfaces.

What is Static Friction?

The question asks about the friction experienced by a body "when the body tends to move". This specific scenario describes the situation where an object is at rest, and a force is applied to it, but the applied force is not yet large enough to overcome the friction and start the motion. The friction force that acts in this situation, opposing the initiation of motion, is known as static friction.

Static friction is a variable force. Its magnitude increases with the applied force, up to a maximum value. Once the applied force exceeds this maximum static friction, the body starts to move.

Comparing Different Types of Friction

Let's look at the other options to understand why they don't fit the description "when the body tends to move":

• Sliding friction: This is the friction that acts when one surface is sliding over another surface. The body is already in motion.
• Dynamic friction: This is often used as a general term for friction when there is relative motion between surfaces, encompassing sliding and sometimes rolling friction. It is the friction experienced by a body that is already moving.
• Rolling friction: This is the friction that acts when a body rolls over a surface. The body is in motion, specifically rolling motion.

Only static friction describes the friction force that exists when a body is at rest but an external force is being applied, making it "tend to move".

Conclusion

Based on the definitions, the friction experienced by the body when the body tends to move, but is not yet in motion, is static friction.