Final answer:
When chalk screeches on a chalkboard, it is due to the chalk periodically overcoming static friction and moving momentarily due to kinetic friction, which is lower in force. This cycle of stick-slip creates the typical sound. Static friction is the force that is most likely to produce the greatest amount of force on the chalk.
Step-by-step explanation:
When pushing a piece of chalk across a chalkboard, the sound produced is due to the chalk alternating between slipping and sticking to the board. This occurs because the kinetic friction is less than static friction. Initially, the chalk sticks to the board (static friction) and as you apply force, the frictional force increases until it reaches its maximum. If you push hard enough, the chalk slips (kinetic friction takes over), which is easier to overcome than static friction. However, as the movement pauses, static friction builds up again, causing the cycle to repeat, leading to the familiar screeching sound.
Static friction responds to an applied force up to a certain limit until the object begins to move. After the chalk starts moving, which signifies that it has overcome the static friction, it then deals with kinetic friction—which is typically lower than static friction. This difference explains why it's easier to keep an object moving once it's started. As for other types of friction mentioned, such as fluid friction and rolling friction, they are not as pertinent to the piece of chalk on a board since it isn't passing through a fluid, nor is it rolling.