Question

Explain static friction with the formula.

Answer 1

Static friction.

Friction occurs due to the property of the surface called roughness

1. Friction causes resistance to the motion between two object
2. Friction is also proportional to the normal force acting on the surface of contact
3. The frictional force that occurs before any motion takes place is called static friction
4. The maximum value that static friction can attain is given by the equation $F_s=\mu N$
5. Here $\mu$ is called the coefficient of static friction and N is the normal force. $\mu$ is the property of surfaces in contact
6. Static friction is caused by adhesion force or the temporary force of bonding between the molecules of object and surface.
7. Also, there is an interlocking of valleys and mountains on the surface of the object
8. To understand the working of static friction let us take an example Let $N=100N,{\mu }_s=0.5$
9. The object will not move until a force of $\mu N=50N$ or less is applied\
10. When the force applied is greater than 50N the frictional force is still 50 and the object starts moving as friction can no longer keep it static
11. The friction force suddenly changes to kinetic friction and the object keeps moving.
12. The graph below shows static friction as a function of applied force