Final answer:
When a constant horizontal force is applied to a block on a horizontal spring, it could cause the block to oscillate in simple harmonic motion. The presence of friction introduces a force opposing the motion, which can dampen the oscillations or, if the applied force persists, it may create a new equilibrium. Friction always acts in opposition to motion, never in the same direction.
Step-by-step explanation:
When a constant horizontal force is applied to a block, the dynamics and effects observed depend on various factors such as friction, mass of the block, and whether any other forces act upon it. If we are discussing a block in the context of a horizontal spring, as mentioned in the question, the dynamics could be related to simple harmonic motion (SHM). In the absence of friction, when a constant force is applied and then removed, the block attached to the horizontal spring would oscillate about an equilibrium position, where the net force is zero.
However, if there's friction, the block will experience a frictional force opposing its motion. This frictional force reduces the kinetic energy of the block, diminishing the amplitude of the oscillation over time, until the block comes to rest. If the constant force persists, it may overcome the frictional force causing the block to accelerate in the direction of the applied force until a new equilibrium is reached where the applied force and the frictional force balance each other out.
It's important to emphasize that friction acts in the opposite direction of the block's motion, contrary to the supplied incorrect statement that suggests friction would enhance the block's motion. Friction always opposes the motion between two surfaces in contact. Therefore, if the constant horizontal force applied to block A is greater than the frictional force opposing it, the block will accelerate.