Final answer:
The cyclist is subject to balanced forces while pedaling at a constant speed against a SON drag. The pedaling force is equal and opposite to the drag force. Without the value of the drag force, the actual power output cannot be calculated.
Step-by-step explanation:
The cyclist and the bicycle are subject to several forces while pedaling with a constant speed despite a SON drag. Since it is given that the cyclist moves at a constant speed, we can infer that the forces are balanced. This implies that the force generated by the cyclist through pedaling is equal in magnitude and opposite in direction to the drag.
The drag force, being the only external force mentioned that opposes the motion, must be equal to the force exerted by the cyclist while pedaling. The magnitude of this force can be calculated using Newton's second law: F = ma. However, because the speed is constant, acceleration (a) is zero, and thus we don't use this equation directly; instead, we rely on the balance of forces discussed. Here, we know the drag force (Fdrag) equals the cyclist's pedaling force (Fpedaling).
The power expended is given by the formula Power = Force × Velocity, which in this case will be the product of the pedaling force and the cyclist's velocity. So, if we had the force value, we could calculate the power as P = Fpedaling × v, where v is the constant speed (4 m/s). Since the forces are balanced and there's no acceleration, the force exerted by the cyclist can be inferred to be equal to the drag force acting on them. Without the value of the drag force, we cannot calculate the actual power output.