What is the difference between Archimedes principle and the law of floatation.
Plz...fast...
Siddharth Subramanian answered this
Archimedes principle is based on the weight of the object to push the object upward.
Law of floation is the priciple which tells us about the density of the object with the liquid in which it is placed.
Law of floation is the priciple which tells us about the density of the object with the liquid in which it is placed.
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Huda answered this
This answer is kinda long but here it is:
Let’s start by watching what happens as the object moves down into the water. You can use a clear measuring cup or a graduated cylinder. Pour water into the cup until it reaches a line on the cup. Record the volume of the water. Tie a string to a metal object. I used a steel bolt and nut. As you lower the object into the water, the total volume will increase. You can determine increase by recording the new volume and subtracting the original volume.
Now, I want you to think about how the water moved upward. What caused the water to move upward?
Let’s use a 100 g piece of wood. The density of the 0.7 g/ml
Volume = 100 g ÷ 0.7 g/ml = 142.9 ml
Since the wood is floating, the water must be supporting the weight of the wood.
Weight of wood = 0.1 kg * 9.8 = 0.98 N
Weight of displaced water = 0.98
Mass of displaced water = 0.98 ÷ 9.8 = 0.100 kg = 100g
Density of water = 1 g/ml
Volume of displaced water = 100 g ÷ 1 g/ml = 100 ml
Volume of wood = 142.9 ml
So, the wood 100 ml of the total 142.9 ml of the piece of wood is submerged.
The only difference between this situation and the one above is the density of the object. The density of the steel bolt and nut is greater than water so it sinks.
The density of a floating object is less than water so it floats.
In this situation, the object will move down until it has displaced enough water to support it.
So the object will move down until the weight of the volume of displaced water equal its weight.
As the object is lowered into the water, the bottom surface of the object exerts a force on the water underneath it. If you lower hand into water, you will feel the water pushing up on the bottom surface of your hand.
The water that is directly under the bottom surface of the object is exerting an upward force on the bottom surface of the object.
The water that is directly under the bottom surface of the object cannot move down unless the rest of the water moves somewhere. If you lower the object quickly, you may see the motion of the water is it moves down, and sideways, and upward; causing the top surface of the water to rise.
As you hold the string so the object is totally immersed under the water, neither the water nor the object will move.
Now the system is at equilibrium. This means the downward force exerted by the object equals the upward force exerted by the water.
So this downward force exerted by the object actually caused a specific volume of water to move upward. The volume of water that has been moved equals the volume of the object! So, this downward force exerted by the object actually caused a volume of water equal to the volume of the object to move upward. So, this downward force exerted by the object is actually supporting the weight of the volume of the water that moved upward.
The water that is directly under the bottom surface of the object is exerting an upward force on the bottom surface of the object. Since the system is at equilibrium, this upward force must equal the downward force exerted by the object.
This downward force exerted by the object is supporting the weight of the volume of the water, so the upward force must equal the weight of the volume of the water that was displaced.
This upward force is called the buoyant force.
The object now has 2 vertical forces!
The weight is pulling it down, and the buoyant force is pushing it up.
The net force on the object = Weight – Buoyant force
As you lowered the object into the water, the net force on the string = Weight – Buoyant force
Before you lowered the object into the water, the force on the string = Weight of object
As you lowered the object into the water, you can feel the decrease of the force required to support the object.
It really does feel like the object is losing weight!!
Example
Density of steel = 7.75 g/ ml
Mass of bolt and nut = 100 g
Volume of steel = 100 g ÷ 7.75 g/ ml = 12.9 ml
Weight of steel = 0.1 kg * 9.8 = 0.98 N
Volume of displaced water = Volume of steel =12.9 ml
Density of water = 1 g/ml
Mass of displaced water = 12.9 g
Weight of displaced water = 0.0129 kg * 9.8 = 0.12642 N
Buoyant force = 0.12642 N
Net force = Weight of steel – Buoyant force
Net force = 0.98 – 0.12642 = 0.85358N
The bolt and nut apparently lost 0.85358N of weight as they we completely immersed into the water.
My second question is that the law of flotation states that an object floats in a liquid if the weight of the object is equal to the weight of the liquid displaced by the submerged part of the object.
I know an easy way to determine the fraction that is under water!
The Density ratio equals the fraction of volume of the object that is under the surface of the liquid.
Density ratio = Density of object / Density of liquid
0.7 / 1 = .7
This means 7/10th of the wood block is under water.
0.7 * 142.9 = 100.03 ml under water
I hope this helps
Let’s start by watching what happens as the object moves down into the water. You can use a clear measuring cup or a graduated cylinder. Pour water into the cup until it reaches a line on the cup. Record the volume of the water. Tie a string to a metal object. I used a steel bolt and nut. As you lower the object into the water, the total volume will increase. You can determine increase by recording the new volume and subtracting the original volume.
Now, I want you to think about how the water moved upward. What caused the water to move upward?
Let’s use a 100 g piece of wood. The density of the 0.7 g/ml
Volume = 100 g ÷ 0.7 g/ml = 142.9 ml
Since the wood is floating, the water must be supporting the weight of the wood.
Weight of wood = 0.1 kg * 9.8 = 0.98 N
Weight of displaced water = 0.98
Mass of displaced water = 0.98 ÷ 9.8 = 0.100 kg = 100g
Density of water = 1 g/ml
Volume of displaced water = 100 g ÷ 1 g/ml = 100 ml
Volume of wood = 142.9 ml
So, the wood 100 ml of the total 142.9 ml of the piece of wood is submerged.
The only difference between this situation and the one above is the density of the object. The density of the steel bolt and nut is greater than water so it sinks.
The density of a floating object is less than water so it floats.
In this situation, the object will move down until it has displaced enough water to support it.
So the object will move down until the weight of the volume of displaced water equal its weight.
As the object is lowered into the water, the bottom surface of the object exerts a force on the water underneath it. If you lower hand into water, you will feel the water pushing up on the bottom surface of your hand.
The water that is directly under the bottom surface of the object is exerting an upward force on the bottom surface of the object.
The water that is directly under the bottom surface of the object cannot move down unless the rest of the water moves somewhere. If you lower the object quickly, you may see the motion of the water is it moves down, and sideways, and upward; causing the top surface of the water to rise.
As you hold the string so the object is totally immersed under the water, neither the water nor the object will move.
Now the system is at equilibrium. This means the downward force exerted by the object equals the upward force exerted by the water.
So this downward force exerted by the object actually caused a specific volume of water to move upward. The volume of water that has been moved equals the volume of the object! So, this downward force exerted by the object actually caused a volume of water equal to the volume of the object to move upward. So, this downward force exerted by the object is actually supporting the weight of the volume of the water that moved upward.
The water that is directly under the bottom surface of the object is exerting an upward force on the bottom surface of the object. Since the system is at equilibrium, this upward force must equal the downward force exerted by the object.
This downward force exerted by the object is supporting the weight of the volume of the water, so the upward force must equal the weight of the volume of the water that was displaced.
This upward force is called the buoyant force.
The object now has 2 vertical forces!
The weight is pulling it down, and the buoyant force is pushing it up.
The net force on the object = Weight – Buoyant force
As you lowered the object into the water, the net force on the string = Weight – Buoyant force
Before you lowered the object into the water, the force on the string = Weight of object
As you lowered the object into the water, you can feel the decrease of the force required to support the object.
It really does feel like the object is losing weight!!
Example
Density of steel = 7.75 g/ ml
Mass of bolt and nut = 100 g
Volume of steel = 100 g ÷ 7.75 g/ ml = 12.9 ml
Weight of steel = 0.1 kg * 9.8 = 0.98 N
Volume of displaced water = Volume of steel =12.9 ml
Density of water = 1 g/ml
Mass of displaced water = 12.9 g
Weight of displaced water = 0.0129 kg * 9.8 = 0.12642 N
Buoyant force = 0.12642 N
Net force = Weight of steel – Buoyant force
Net force = 0.98 – 0.12642 = 0.85358N
The bolt and nut apparently lost 0.85358N of weight as they we completely immersed into the water.
My second question is that the law of flotation states that an object floats in a liquid if the weight of the object is equal to the weight of the liquid displaced by the submerged part of the object.
I know an easy way to determine the fraction that is under water!
The Density ratio equals the fraction of volume of the object that is under the surface of the liquid.
Density ratio = Density of object / Density of liquid
0.7 / 1 = .7
This means 7/10th of the wood block is under water.
0.7 * 142.9 = 100.03 ml under water
I hope this helps
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