Final answer:
When the roller coaster is at rest at the start of the ride, the forces are balanced. When the roller coaster is launched, the forces are unbalanced.
Step-by-step explanation:
When the roller coaster is at rest at the start of the ride, the forces acting on it are balanced. This means that the forces pushing and pulling on the roller coaster are equal in magnitude and opposite in direction, resulting in no net force on the coaster.
When the roller coaster is launched, the forces acting on it are unbalanced. This means that there is a net force on the coaster, causing it to accelerate. The force pushing the coaster forward (such as the propulsion system or gravity) is greater than the forces acting in the opposite direction (such as air resistance or friction).
Therefore, the correct answer is balanced, unbalanced.