Model ABM yang saya hasilkan ini menggunakan kertas warna dan juga ‘sugar paper’. Saya mengambil masa selama tiga hari untuk menyiapkan model ini. Alhamdulillah akhirnya model fizik yang berkisar tentang belon udara panas yang menggunakan prinsip Archimedes ini dapat saya siapkan. (^_^)
Archimedes’s principle states that when an object is suspended in a fluid, the buoyant force acting on an object is equal to the weight of the fluid displaced. As a consequence of Archimedes’s principle, an object will float in a fluid if it is less dense than the fluid.
Ordinarily people think of a fluid as being a liquid, however in science a fluid is defined as either a liquid or a gas. Air is therefore a fluid and Archimedes’s principle applies to floating in air as well as floating in a liquid.
Hot Air Balloons
The balloon filled with hot air is less dense than when it is filled with cool air. For the balloon to rise and lift the basket and passengers off the ground, the hot air in the balloon must have a low density. The balloon, basket, and passengers combination must weigh less than the total amount of air displaced by the balloon. Then the upward buoyant force exceeds the downward weight (gravitational force).
Helium filled balloons float by the same principle because helium gas is much less dense than air.
The hot air filling the balloon reduces its density according to the ideal gas law. When its total density is less than the density of air, it floats according to Archimedes’s principle.
The density difference is greater when the air temperature is cooler, so hot air balloons are often inflated in the cooler predawn hours.
Enjoy watching hot air balloons soar into the air, or take a balloon flight. Understanding the physics that causes them to silently float upwards increases their beauty. Fundamental physical principles are beautiful to the mind and contribute to visual beauty.
source : http://wiki.answers.com