Final answer:
The student's problem involves the application of Newton's second law and the concept of kinetic friction to determine the acceleration of a sled and the force required for constant velocity.
Step-by-step explanation:
The question involves finding the acceleration of a sled given a certain applied force, the coefficient of kinetic friction, and the mass of the sled. To solve part (a) of this problem, we need to apply Newton's second law (F=ma) and consider the x (horizontal) component of the applied force as well as the force of friction. The net force acting on the sled will be the difference between these two forces. For the sled to have constant velocity (part b), the net force must be zero, so the applied force needs to exactly balance the frictional force.