Final answer:
The sled being pulled at a constant speed by a father experiences gravity, friction, tension in the rope, and air resistance, with all forces balanced according to Newton's First Law.
Step-by-step explanation:
When a father uses a rope to pull a child on a sled at a constant speed, the forces acting upon the sled are gravity, friction, tension in the rope, and air resistance. Gravity acts downward, giving the sled its weight. Friction is the force that opposes the motion of the sled, acting parallel to and opposite the direction of movement. The tension in the rope is the force exerted by the father pulling the sled, and air resistance is a force caused by the sled moving through the air, albeit typically small at low speeds. According to Newton's First Law, since the sled is moving at a constant speed, the net force is zero, meaning that all these forces are balanced.