Physics  Buoyant Force
posted by Phillip .
A piece of metal weighs 50.0 N in air, 36.0 N in water, an 41.0 N in an unknown liquid. Find the density of the unknown liquid.

find volume of metal first
Buoyant force in water = 14 N = weight of water displaced in 1 g gravitational field
mass of water displaced = 14 N/9.8 m/s^2 = 1.43 kg of water displaced
the density of water = 1,000 kg/m^3
so
volume of metal = 1.43*10^3 m^3
Buoyant force in unknown = 50  41 = 9 N
so mass of unknown displace = 9/9.8 = .918 kg
so the density of unknown = .918kg/1.43*10^3 = 642 kg/m^3
or 64.2% of the water density 
I'm confused about the "1 g gravitational field". What's the 1 g referring to and why is it 1 g?

g is the acceleration of gravity which is about 9.8 m/s^2 on the surface of earth.
Since the weights were given in Newtons, a unit of force, not mass, I used weight in Newtons = mass in kilograms * acceleration in meters / second squared to find the mass in kilograms. 
where did you got the buoyant force in water?

It's well known it doesn't need to be given (like the gravitational force)

Take the actual weight (in air) of the object and subtract the weight(apparent) the objects seems to have in the unknown fluid ie take 50N and subtract 36N to get 14N which is the buoyant force/upthrust.
Respond to this Question
Similar Questions

Chemistry
O.k. I am confused. So here is what I did. Mass of empty flask plus stopper: 37.34g mass of stoppered flask plus water: 63.67g Mass of stoppered flask plus liquid: 52.01g Mass of water: 63.67  37.34= 26.33 Volume of Flask(density … 
Urgent  Physics
The Ushaped glass tube in the figure below contains two liquids in mechanical equilibrium: sea water of density 1.025 kg/L, and an unknown liquid of density ρ. The unknown liquid is in the left tube, floating on top of the water … 
physics
A column of water of height h1 = 70.0 cm supports a column of an unknown liquid h2 = 30.0 as suggested in the figure (not drawn to scale). Assume that both liquids are at rest and that the density of water is 1.0x103 kg/m3. Determine … 
college Chemistry
1. If 25 grams of Iron (III) hydroxide is dissolved in a 500mL volumetric flask, what is the Molarity of the solution? 
AP CHEMISTRY
The molar mass of an unknown organic liquid (M~100) is determined by placing 5 mL of the liquid in a weighed 125mL conical flask fitted with a piece of Al foil with a pin hole in it. The flask is heated in a boiling water bath until … 
Chemistry
three separate questions 1. An empty graduated cylinder weighs 82.450 g. When filled to 50.0 mL, with an unknown liquid it weighs 110.810 g. What is the density of the unknown liquid? 
Physics Fluids
A column of oil of height 70.0 cm supports a column of an unknown liquid. Assume that both liquids are at rest and that the density of the oil is 840 kg/m^3. Determine the density of the unknown liquid. 
Physics Fluids
When a block of volume 1.00 × 10–3 m3 is hung from a spring scale, the scale reads 10.0 N. When the same block is then placed in an unknown liquid, it floats with 2/3 of its volume submerged. The density of water is 1.00 × 103 … 
physics
a piece of metal of density 7800kgm3 weighs 20N in air. Cal. The apparent weight of th metal when completely immersed in a liquid of density 830kgm3 
Physics
A piece of metal weighs 51.8 N in air, 37.2 N in water, and 42.6 N in an unknown liquid. Find the density of the metal. Answer in units of kg/m^3 Find the density of the unknown liquid. Answer in units of kg/m^3