Lesson 16 : Summary on Frictional force
- Friction is a resistive force that acts to oppose the motion or attempted motion of one surface across another.
- It arises from the interactions between the surfaces’ microscopic irregularities, regardless of how smooth they may appear.
- There are two primary types of friction: static and kinetic.
- The irregularity of the surface is directly proportional to the friction produced.
- Heat is produced due to friction which can be experienced by rubbing hands together quickly.
- When an object is about to slide over the surface of another object, the highest amount of static friction comes into play. This is known as Limiting Friction
- Static friction acts when two surfaces are in contact but not moving relative to each other.
- It prevents the surfaces from sliding past one another until a certain threshold is reached.
- Kinetic friction, on the other hand, acts when one surface is sliding over another, and it is usually less than static friction.
- Friction plays a crucial role in our everyday lives.
- It enables us to walk without slipping, drive cars safely by providing the necessary grip between tires and the road, and allows parachutes to slow down descent by creating air drag.
- Friction also keeps nails in place and prevents light bulbs from unscrewing themselves. However, friction can also be a hindrance, causing wear and tear on machinery and making it harder to move objects.
- The coefficient of friction (μ) quantifies the amount of friction between two surfaces and varies depending on the materials in contact.
- It is the ratio of the frictional force (Ff) to the normal force (FN) pressing the surfaces together. The static friction force (F_s) can vary from zero up to a maximum value (μs * FN), where μ_s is the coefficient of static friction. Kinetic friction (Fk), represented as μk * FN, where μk is the coefficient of kinetic friction, is usually less than static friction.
- Understanding friction involves using free-body diagrams to visualize forces acting on an object, crucial for solving problems using Newton’s second law.
- These diagrams include only the forces directly acting on the object, such as gravitational force, normal force, applied force, and frictional force. In dynamic situations, tension forces also come into play when objects are connected by strings or cables.
- Tension acts along the string’s length and affects both the object and the person exerting the force.