Question

2 is the roller coaster at the top of the hill balanced or unbalanced? 3 what would cause the roller coaster to change its motion?

Explanation:

1. At the top of the hill, the roller - coaster is unbalanced. Gravity pulls it downwards and there is no equal and opposite force in the horizontal direction to keep it completely still in a balanced state.
2. Unbalanced forces such as gravity, friction between the coaster and the track, and the normal force from the track's shape changes would cause the roller - coaster to change its motion. Gravity causes it to accelerate downwards on slopes, friction opposes its motion, and changes in the track's curvature change the normal force acting on it.

Answer:

1. Unbalanced
2. Unbalanced forces like gravity, friction, and changes in normal force.