Question

While an astronaut on planet X, you find a sample of an unknown liquid. Without your fancy equipment you decided to measure the mass of your spoon (25 grams, using local gravity) in and out of the liquid. In the liquid the scale reads 17.3 grams and it reads 18.9 grams in water. What is the density and the identity of the unknown liquid

Answer 1

here,

the mass of spoon in air , m1 = 25 g = 0.025 kg

when dipped in water

let the volume of spoon be V

the mass in water = 17.3 g = 0.0173 kg

0.025 * 9.81 - 0.0173 * 9.81 = density of water * V * g

7.7 * 10^-3 = 1000 * V

V= 7.7 * 10^-6 m^3

when dipped in unknown liquid

let the density of liquid be p'

the mass in liquid = 18.9 g = 0.0189 kg

weight in air - weight in liquid = buoyant force

0.025 * 9.81 - 0.0189 * 9.81 = p' * V * g

6.1 * 10^-3 = p' * 7.7 * 10^-6

p' = 792.2 kg/m^3

the density of unknown liquid is 792.2 kg/m^3

the liquid is Methanol