12. When two objects interact through the gravitational force between them, the more massive one has a lower acceleration than the less massive object.
13. A student walks 20 m north, 10 m south, and 3 m north. To have a displacement of 0 m, the student should walk 13m toward the south.
14. Jennifer's thinking is not supported by Newton's third law of motion because during the collision, the force on her bumper car must be equal in size and opposite in direction to the force on her father's bumper car.