Why does sugar dissolves easily in water but sand doesn’t

Table sugar dissolves in water because when a sucrose molecule breaks from the sugar crystal, it is immediately surrounded by water molecules. The sucrose has hydroxyl groups that have a slight negative charge. ... Sand can't dissolve in waterbecause the 'spaces' in between the water particles. :)

temp rises, and expansion

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.