What is the force acting on the block that is directed to the left called?
The correct answer and explanation is:
The force acting on a block that is directed to the left is commonly called frictional force (if the block is sliding or attempting to slide on a surface) or simply a force opposing motion.
Explanation:
When a block moves or tries to move on a surface, there is often a force acting in the opposite direction to its motion. If the block is moving to the right, the force directed to the left usually represents friction. Friction is a resistive force that occurs between the surfaces of two objects in contact. Its role is to oppose the relative motion or attempted motion between those surfaces.
Friction arises due to the microscopic irregularities between the surfaces that interlock as the objects slide or try to slide past each other. The magnitude of friction depends on the nature of the surfaces and the normal force pressing them together.
In other cases, if no motion is involved yet, the force directed to the left might be a resisting force such as tension, applied force, or air resistance depending on the situation.
For example, if a person pushes a block to the right, the friction force will act to the left. If the block is at rest and a force tries to move it to the right, static friction will act to the left to prevent movement.
Frictional force is calculated using the formula:
Ffriction=μ×NF_{\text{friction}} = \mu \times N
where μ\mu is the coefficient of friction (either static or kinetic) and NN is the normal force, which is the perpendicular force exerted by the surface on the block.
In summary, the force directed to the left acting on the block is usually friction if it opposes motion. This force plays a crucial role in everyday activities such as walking, driving, and holding objects because it prevents slipping and enables controlled movement.