Calculating Buoyant Force for a Submerged Beach Ball

  • Thread starter jsalapide
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In summary, the conversation discussed the relationship between the density of an object and the density of a liquid when the object is completely submerged. It also mentioned using the formula p=m/v to calculate the buoyant force on an object. The conversation concluded with a question about the correctness of the answer obtained using this method.
  • #1
jsalapide
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1.A beach ball has a volume ofHow much force would you have to exert to hold this beach completely under water?

I learned that for an object that is completely submerged in a liquid, the density of the object is equal to the density of the liquid.

I used the formula p=m/v to get the mass of the ball. I set p as the density of water which is 1000 kg/m^3. The answer I got was 50 kg. Then I multiply it to 9.8 m/s^2 to get the buoyant force.

My answer was 490 N...

Am I correct?
 
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  • #2
jsalapide said:
I learned that for an object that is completely submerged in a liquid, the density of the object is equal to the density of the liquid.

No. The buoyant force on the object is equal to the weight of the liquid displaced. Holding the beach ball under water replaces the volume of water with the volume of air. The difference in the weight of the air and the water displaced is what gives the ball lift.

If this is what you are doing with your calculation, (I can't see your volume), then you have the right method, if only the wrong expression of what you are doing.
 
  • #3
ooops.. sorry I forgot.

The volume of the ball is 0.050 m^3..

Is my answer correct?
 
  • #4
jsalapide said:
ooops.. sorry I forgot.

The volume of the ball is 0.050 m^3..

Is my answer correct?

.05 m³ is 50 kg is 490 N Looks ok then.
 
  • #5
Thanks for the help sir...!
 

What is buoyant force?

Buoyant force is the upward force exerted by a fluid on an object immersed in it. It is equal to the weight of the displaced fluid and acts in the opposite direction of gravity.

How do I calculate buoyant force?

The buoyant force can be calculated by multiplying the density of the fluid, the acceleration due to gravity, and the volume of the displaced fluid. The formula is Fb = ρ x g x V, where ρ is the density, g is the acceleration due to gravity, and V is the volume.

What is density?

Density is a measure of how much mass is contained in a given volume of a substance. It is usually expressed in units of mass per unit volume, such as grams per cubic centimeter or kilograms per liter.

How do I calculate density?

Density can be calculated by dividing the mass of an object by its volume. The formula is ρ = m/V, where ρ is density, m is mass, and V is volume. The unit of density will depend on the units used for mass and volume.

What is the relationship between buoyant force and density?

The buoyant force is directly proportional to the density of the fluid and the volume of the displaced fluid. This means that the greater the density of the fluid or the larger the volume of the displaced fluid, the greater the buoyant force will be.

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