When a kid moves up and down on a swing with a little effort, the swing is beneath its natural frequency, above its natural frequency, or at its natural frequency? And a person sits on a swing. If the person sits still, the swing oscillates backward and forward at its natural frequency. If, rather, two people sit on the swing, the new natural frequency of the swing is more than it was with one person, the similar as it was with one person, or less than it was with one person?