Buoyant force/density problem

  • Thread starter jsalapide
  • Start date
  • Tags
    Buoyant
In summary, the conversation discusses the concept of buoyancy and how it applies to an object, specifically a beach ball, that is completely submerged in a liquid. The formula for calculating buoyant force is mentioned, as well as the correct method for determining the mass of the beach ball. The conversation also touches on Archimedes' principle and how the density of the object affects its buoyancy. Finally, the conversation concludes with a question about the downward force needed to keep the beach ball underwater.
  • #1
jsalapide
40
0
1.A beach ball has a volume of 0.050 m^3. How much force would you have to exert to hold this beach ball completely under water?

can somebody help me plss,,,,
 
Physics news on Phys.org
  • #2
what have you tried so far?

There is a template for homework questions and a separate section.
 
  • #3
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?
 
  • #4
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.
This is not correct. Look up Archimedes principle.
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.
For all practical purposes, the density of the air filled beach ball can be neglected...that is, assume it has no weight.
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?
The buoyancy force is 490N upward. What downward force must be applied to keep the ball completely underwater?
 

1. What is the buoyant force?

The buoyant force is the upward force exerted by a fluid (such as water or air) on an object immersed in it. It is caused by the difference in pressure between the top and bottom of the object.

2. How is buoyant force related to density?

Buoyant force is directly proportional to the density of the fluid and the volume of the object. This means that the denser the fluid, the greater the buoyant force, and the larger the volume of the object, the greater the buoyant force.

3. What is Archimedes' principle?

Archimedes' principle states that the buoyant force on an object in a fluid is equal to the weight of the fluid that the object displaces. This means that the more fluid an object displaces, the greater the buoyant force acting on it.

4. How do you calculate the buoyant force on an object?

The buoyant force can be calculated using the formula Fb = ρVg, where Fb is the buoyant force, ρ is the density of the fluid, V is the volume of the object, and g is the acceleration due to gravity. Alternatively, you can also calculate it by multiplying the weight of the fluid displaced by the object by the acceleration due to gravity.

5. Can an object sink or float in a fluid with the same density?

Yes, an object can sink or float in a fluid with the same density. This is because factors such as shape, size, and weight also play a role in determining whether an object will sink or float. An object with a larger surface area will experience a greater buoyant force and is more likely to float, while an object with a smaller surface area is more likely to sink.

Similar threads

  • Introductory Physics Homework Help
Replies
11
Views
389
  • Introductory Physics Homework Help
Replies
4
Views
3K
  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
13
Views
2K
  • Introductory Physics Homework Help
Replies
16
Views
1K
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
1K
  • Introductory Physics Homework Help
Replies
7
Views
3K
  • Introductory Physics Homework Help
Replies
10
Views
3K
  • Introductory Physics Homework Help
Replies
4
Views
3K
Back
Top