Question

To know how many Helium balloons are needed to lift a girl who weighs 35 kg, one intends to measure how much weight a single balloon can lift. A scale that is sensitive to 0.1 g, small pieces of copper, and an ordinary party balloon show that a balloon with a volume of about 2 l can lift 2g of copper.
How many balloons will it take to lift the girl?
Does this agree with the result obtained if you use Archimedes' principle and know that the air density at 20∘C is 1.2 kg / m3 and the density of helium is 0.17 kg / m3?

Answer 1

Volume of a single ballon =al and it Candift og maso. The maso of girl & 35kg = 3500om Sono Of ballons needed ! - 35000 = 17000 balloons 2 bortia anower. Ano no ot balloons * maso it com lift- 35kg. Now by Arclemedies principle. wt of air dix planced= Sair* Vballong. 1.2kg x2x103 xg 2-49m *g. balloon Wt of beli tim filled - 0.17X203 x 2x103xg = 0:34 84 m tf. m3 up thrust force on = = Fret =2.4 -0.34 Lot ↑ Fap -2.06g equivalent 80 this result agree with assumptions. Lust