Why is it night?

A photo from a hotel room in Las Vegas. Why is it night? Day and Night cycles are based on which parts of the earth the rays of light from the sun hit. At this particular time, the earth had rotated to a particular point where Las Vegas was on the side of the earth not illuminated by the Sun. There is no moon in this picture, but it was in the sky that night. The moon moves around the earth in an elliptical pattern while also revolving around it's own axis. As it moves around, only one side of the moon is visible to the earth and this determines what kind of moon there is. I think on this particular night, it was a waxing gibbous.

Windchimes

How does this wind chime stay balanced and not tip to one side or the other? The wind chime is at an equilibrium. There are equal torques pulling down on each side of the wind chime which are balancing it out and preventing the wind chime from tilting to one side over the other. If one of the support strings or bells were to be removed, there would be less of a torque in one place and no equilibrium so the wind chime would tilt.

Soda Can Physics

This is a picture of a can of coke on the edge of my dresser. How is it not falling off? The reason for this is the location of the center of gravity of the coke bottle. If we move downwards from the center of gravity, there is enough a support base to support the object and keep it from falling. If the can was moved further to the right, there would be no support under the can and it would fall off the table. Having some kind of support under the center of gravity is crucial in keeping an object balanced.