TOPIC 05-ARCHIMEDES PRINCIPLE AND LAW OF FLOATATION
1.ARCHIMEDES PRINCIPLE
An apparent weight:
Is the weight of the body when itโs partially or totally immersed in liquid.
Up thrust - is upward force exerted by the fluid on the body.
Fluid - is a liquid or gas.
EXPERIMENT
- Tie a solid with a string and suspend it from a spring.
- Find the weight of a body in air, call it W1.
- Find the weight of a body when it is partially immersed in water contained in a beaker, call it W2.
- Find the weight of a body when itโs totally immersed in water, call it W3.
- Remove a body from the water, dry it and find its weight, call it W4.
- It will be observed that W1>W2>W3.
Also W1 = W4
- This shows that the weight of a body when immersed in water is equal to its weight after it has been removed in water.
- This result shows that there is apparent loss of weight of the body when it is partially or totally immersed in water.
- That loss of weight is not a real loss.
- An apparent loss = weight of a body โ apparent weight of a body in liquid.
From that experiment
An apparent loss = W1 โW2
A liquid exerts an upward force in a body when it is partially or totally immersed in it.
Upthrust = an apparent loss in weight = W1โW2
Example:
1. A body weighs 3.0N in air. When it is totally (completely) immersed in liquid it weighs 2.2N. Find the upthrust experienced by the body.