They will dissolve much quicker in warm or hot water than in cold water.
water!
Yes
Liquid
it is better to use sugar cubes
I never heard of crushed water. Crushed ice (which sugar cubes don't dissolve in at all), but not crushed water. Let's see here: sugar dissolves faster in hot water than cold. And crushed sugar cubes, because the sugar has more surface area, dissolve faster than cold ones.
Granulated sugar has more surface area exposed to the coffee, therefore it will dissolve faster.
Sugar in something cold would dissolve, if you put sugar into something hot then it would melt and then dissolve.
it does because it is white and white dissolves!
Hot water
sugar cubes dissolve faster than limestone
Let's imagine the following objects first: Sugar cubes are solid blocks, each with a comparatively larger volume. Granulated sugar is fine and particulate, and each grain has a very small volume. It is only logical that when comparing one block of sugar to one grain of sugar, that the grain dissolves faster because it has a smaller volume (less to dissolve), and the surface area to volume ratio is much higher.
Probably because the surface area of the sugar granules is larger, more sugar molecules are exposes to water at once.