Answer:
The forces acting on the marble are; parallel and perpendicular forces.
When Andrew pokes the marble, he gave it an impulse. The movement of the marble is slowed down by friction and drag from the surrounding air molecules. As the marble rolls down the ramp, its weight pulls it down.
Explanation:
This is a simply experiment to determine effect of a force on an object. As it rolls down the ramp, parallel forces to the surface of the ramp and perpendicular foces to the surface are acting.
The initial impulse given produces motion and a change in momentum of the object.
The surface of the ramp applies an oppositional force to the direction of motion of the marble and same as the surrounding air molecules.
But the ramp continues to roll down due to the force of gravity and its mass.