Question

The density of bubble gum is about 920  kg/m^3 . You blow a 8.40-gram wad of gum into a bubble with a measured diameter of 9.50  cm . Assume that all of the gum is in the skin of the bubble.

a) What is the thickness of the bubble? Hint: Think about spreading the bubble into a flat sheet. The surface area of a sphere is 4πr2. give your answer in mm.

b) What had been the thickness of the bubble when the growing bubble was only 1/4 of its final diameter? give your answer in mm.

Answer 1

The volume of the gum is, V = Area thickness = (4tr²) The density is related to volume as follows: d =* The thickness is, m ** ALT" 8.40 g (920 kg/m3) 4-9.50 cm 0.00840 kg (920 kg/m?)47(0.095 m) = 3.22x104 m -0.322 mm

(b) The 1/4 th of the radius is, 1d 12 0.0950 m = 0.0118 m 8.40 g (920 kg/m²) 47 (0.0118) 0.00840 kg (920 kg/m°) 47 (0.0118)?! = 5.2x10 m - 5.2 mm