How does friction affect the motion of a moving object?

Friction is a force that arises when two surfaces come into contact, and it plays a crucial role in the motion of objects. The main effect of friction is that it opposes the relative motion between the surfaces in contact. When an object is in motion, friction acts in the opposite direction to its movement, effectively resisting it. This resistance can result in a decrease in the object's speed or even bring it to a stop if the frictional force is substantial enough compared to the force propelling the object forward.

For example, when you push a box across the floor, friction between the box and the floor tries to prevent the box from sliding, which may slow it down or require more effort to keep it moving. Therefore, the correct answer emphasizes that friction can significantly impact motion by opposing it, highlighting its role in deceleration or stopping an object's movement.