What is the smallest or most specific level of organization you and your neighbors are have in common

Galileo was the first to notice that the moon has craters, valleys, and mountains. how might this have changed people's perception of the moon at the time?

Which is not true about oxygen-17 and oxygen-18?

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.