Calaculate Mass of Cube submerged in oil and water

In summary, to calculate the mass of a cube submerged in oil and water, you can use Archimedes' principle separately for the two parts submerged in the two liquids and add the buoyant forces to balance the weight. Alternatively, you can find the net force acting upward by subtracting the pressure at the bottom from the pressure at the top, and then use F=mg to calculate the mass. It is important to correctly calculate the pressure at the top and bottom of the cube, using the formula P=density*g*height, and to consider the net force acting upward rather than adding the forces.
  • #1
TFM
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0
[SOLVED] Calaculate Mass of Cube submerged in oil and water

Homework Statement



A cube is submerged in water and oil the oil is on top, and forms a layer 10cm thick. the water is underneath and forms another layer 10cm thick. the cube has sides of 10.2cm, and has 2.3cm below the oil water line. the density of the oil is 790kg. I have worked out already the force on the top of the cube is 163 Pa, and on the bottom 1000 Pa. How do you work out the mass of the cube?

Homework Equations



Pressure = Force/Area

Archimedes: The upward force is equal to the weight of fluid displaced by the block (?)

The Attempt at a Solution



Any help would be appreciated

TFM
 
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  • #2
Use Archimedes' separately for the two parts submerged in the two liquids and add the buoyant forces to balance the weight. Hence, find mass. No need to find pressure.
 
  • #3
Am I doing simetghing wrong? I am doing:

F = p*A
A = 0.102^2 = 0.0104

P top = 163
Pressure Bottom = 1000

F top:1.696
F bottom = 10.404
Sum F = 12.10

using F = mg,

m = 1.23kg

But it is wrong?

TFM
 
  • #4
TFM said:
Am I doing simetghing wrong? I am doing:

P top = 163
Pressure Bottom = 1000

TFM

Show how you got these two.
 
  • #5
Therehave been stated as being right, because I am using mastering physics, and have previously calculated them and got them marked correct.

I used P = denstiy*g*height,
Density Oil = 790 (stated in question)
height I calculated as being 2.1cm (0.021m)

Works out as 163 Pa (Did same thing for Water at the bottom, but used the total pressure = pressure caused by the oil on top + the pressure from the water layer from the join to the bottom of the cube.)

The Pressures are gauge pressures, by the way, if that helps?

TFM
 
Last edited:
  • #6
TFM said:
Am I doing simetghing wrong? I am doing:


F top:1.696
F bottom = 10.404
Sum F = 12.10

using F = mg,

m = 1.23kg

But it is wrong?

TFM

Why have you added the forces? Net force acting upward should be F_bottom - F_top.

I still recommend that you learn how to solve using the method I had told you right in the beginning. If the body given is not a cube or parallelepiped, then you won't be able to do it using your way.
 
  • #7
Thanks. Finally got the right answer (0.889kg)

TFM
 

Related to Calaculate Mass of Cube submerged in oil and water

1. How do you calculate the mass of a cube submerged in oil and water?

The mass of a cube submerged in oil and water can be calculated by first finding the volume of the cube, then determining the density of both the oil and water. The mass can then be calculated using the equation: mass = volume x density.

2. What is the formula for calculating the volume of a cube?

The formula for calculating the volume of a cube is V = s^3, where s is the length of one side of the cube.

3. How do you determine the density of oil and water?

The density of a substance can be determined by dividing its mass by its volume. To find the density of oil and water, you can perform a simple experiment by measuring the mass and volume of a known amount of each substance and then dividing the mass by the volume.

4. Can the mass of a cube submerged in oil and water be different from its actual mass?

Yes, the mass of a cube submerged in oil and water can be different from its actual mass. This is because the density of the cube may not be equal to the density of the oil and water. Additionally, there may be air pockets or other factors that can affect the accuracy of the measurement.

5. How can the calculation of mass of a cube submerged in oil and water be useful in scientific experiments?

The calculation of mass of a cube submerged in oil and water can be useful in various scientific experiments, such as determining the density of an unknown substance or studying the principles of buoyancy. It can also be used to understand how different substances interact with each other and their effects on buoyancy and weight.

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