How fast does water evaporate?
A typical cup is around 15cm high and with a diameter of 8cm, giving a surface area of 3.14×0.04×0.04 (circular surface area = pi x(r squared) = 0.00502, and so every second, 0.00502 x 0.000038953kg/s evaporate. This gives 0.000195799g/s. At this rate, a typical cup of water with 753g of water in it (calculated from above dimensions, water = 1000kg/m3) would take 1069hours to completely evaporate, or 44 days.