A similar thing happens at each subsequent hill. Since momentum is the product of velocity and mass, the Rover will have the same magnitude of momentum on each planet. The weight of the Rover is smaller on Mars, but its mass is exactly the same. When the top drawer is opened, and no longer directly over the base of the cabinet, the gravitational force on the drawer exerts a torque on the cabinet. If the gravitational force on the rest of the cabinet is too small to provide a balancing torque to the cabinet, it will tip over.
Friction exerts a centripetal force on the car, directed towards the center of the circular track.
The weight and the normal force balance each other, and so add to zero. The net force is then just equal to the frictional force, directed towards the center of the circle. The moon has a velocity, in a direction which is mostly perpendicular to the direction of the gravitational force the earth exerts on the moon. The result of this arrangement is that the force the earth exerts changes the direction of the moon's velocity by exactly enough to keep it in orbit.