Volume and Density of Unknown Material: Homework Statement

[05holtel]

Homework Statement

A samoke of unknown material weighs 300N in air and 200N when immersed in alcohol of specific gravity 0.7. Find the volume and density of the material

Homework Equations

Specific Gravity = density of material/density of water

Density fluid x volume of fluid x gravity = density material x volume of material x gravity

The Attempt at a Solution

Volume of substance = Density of Fluid x Volume of fluid / Density of material

The density of the substance can be using the specific gravity equation.

I am not sure how to solve for the volume and density though

 

[mgb_phys]

In the alcohol it is pushed up by a force equal to the weight of alcohol displaced.
Since you know the force difference, you can work out the volume of alcohol and so the volume of the thing.

 

[05holtel]

So is it

Fb= V x density x gravity
V = 100N/(700kg/m3 x 9.8)

 

[mgb_phys]

The units balance - you can check the arithmetic by putting the answer back into the question and checking you get the same buoyant force