What is the buoyant force of water on the block?

In summary, the first problem involves finding the buoyant force of an object that weighs 50 N in air and 20 N in water. The second problem involves finding the total mechanical energy of a system with a 20 N/m horizontal spring and a 0.2m amplitude. The formula to use for the second problem is E = 1/2ka^2.
  • #1
future_vet
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Homework Statement


A block of unknown material weighs 50 N in air and 20 N in water. What is the buoyant force of water?

Homework Equations


I know how to calculate density etc. I thought the formula to use was -density x V x g but it's not correct.


Homework Statement


A x Kg mass is attached to a horizontal spring of constant 20 N/m and set into harmonic motion with an amplitude = 0.2m. What is the total mechanical ernergy of the system?

I have no idea what to do... Some help would be greatly appreciated. Thanks!
 
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  • #2
  • #3
I was thinking it would be 50 - 20 = 30 but it seems a bit too simple to be true...
 
  • #4
So for the second:
0.5 * 25 * 0.2^2 = 0.50J ?

THANK YOU!
 
  • #5
It's simple and it's true.

I can't check your second answer because I can't see what the mass is.

[edit] E = 1/2ka^2 - whoops, you don't need the mass, so you're right there also.
 
Last edited:

FAQ: What is the buoyant force of water on the block?

What is buoyancy?

Buoyancy is the upward force exerted by a fluid on an object that is submerged or partially submerged in the fluid. This force is equal to the weight of the fluid that the object displaces.

How does buoyancy work?

Buoyancy works based on Archimedes' principle, which states that the buoyant force on an object is equal to the weight of the fluid that the object displaces. This means that if the weight of the object is less than the weight of the fluid it displaces, it will float; if the weight is greater, it will sink.

What factors affect buoyancy?

The factors that affect buoyancy include the density of the fluid, the volume of the object, and the gravitational force acting on the object. Objects with a higher density than the fluid will sink, while those with a lower density will float. The greater the volume of the object, the greater the buoyant force acting on it. And the strength of the gravitational force will determine how much of the object is submerged.

How is mechanical energy related to buoyancy?

Mechanical energy and buoyancy are related because buoyancy is a type of potential energy. When an object is submerged in a fluid, it experiences an upward force due to the fluid's pressure. This force can do work on the object, giving it potential energy. As the object moves, this potential energy is converted into kinetic energy, representing the mechanical energy of the system.

How can I calculate the buoyant force on an object?

To calculate the buoyant force on an object, you need to know the density of the fluid, the volume of the object, and the acceleration due to gravity. The buoyant force is equal to the weight of the fluid that the object displaces, which can be calculated by multiplying the density of the fluid by the volume of the object and the acceleration due to gravity. This can be represented by the equation Fb = ρVg, where Fb is the buoyant force, ρ is the density, V is the volume, and g is the acceleration due to gravity.

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