Why does a spherometer have three legs​

Recall from geometry that three points determine a plane, so the three legs will always touch the glass.One complete turn of the central screw of the spherometer raises or lowers the center point a set distance which is determined by the size of the thread of the screw and the radius of the disc.

which piece of furniture will have the most inertia and give the furniture movers the most difficulty in moving?  

answer

a 75kg dining table

the inner core.

good luck: )

klicker