It is quite puzzling to see a small stone thrown in water, sinks! On the other hand, a huge iron ship floats on the water surface smoothly. More bewildering is when the same material bodies perform distinctively for example; a small iron pin sinks in the water but not the large iron ship. Doesn’t the size matters here?
If not, then what is it that decides whether a body will float or sink?
In fact, one can see different types of rocks having varying strengths and limits drawn to different levels into the water. It is indeed a deeper conception and one can use numerous examples to investigate floating or sinking of any body. Many could not understand the phenomenon and struggled to achieve the right idea behind it.
When we jump into a large water body such as a swimming pool or river of longer depth, we probably sink. But if we spread our arms and lay straight, cheating the area we cover by kicking the water continuously, we likely to float on water. How do we figure out why a body float or sink in water?
All these encounters were puzzling to the greatest scientist of all times, Archimedes. He experimented with different sizes and masses of bodies to float on water. After long analysis of different bodies and lengthy observations, he reached out to a better version of the sinking phenomenon. He included two important forces that influence the condition of a body while in water , they are- gravitational force and buoyant force.
Since gravity is always same whether a body is outside or inside the water, the force of gravity or weight of a body depends on the mass of the body, as it is the measure of the product of mass of the body and the acceleration due to earth’s gravity.
Buoyant force on the other hand, is the upward force exerted by the water upon the body (completely or partially submerged) due to the pressure exerted on the body by the water. It is the net difference of the water pressure from the bottom of the body and the upward pressure due to the weight of the body. Hence, if the weight of the body is more than the water pressure on it, than we say less amount of buoyant force is exerted on the immersed body. The buoyant force thus depends on the density of the fluid in which a body is immersed.
On the basis of his study, Archimedes concluded that, a body floats when its mass is lesser or equal to the area of fluid (e.g. water) displaced by it. On the other hand, a body sinks, if it possesses the mass larger as compared to the area of fluid (e.g. water) displaced by it. That means a body of lesser or equal density floats on fluid whereas the body with more density sinks. All depends on the densities of the body and the fluid used.
In case of a small iron pin or stone, their masses were higher than the area of water they displaced, which led to sinking. Whereas, in case of large iron boat, the area displaced by it was equal to its mass, that was responsible for the iron boat to float on top of the water. Clearly, when the relative density is lesser than 1, body floats on water. In this way, Archimedes simplified the phenomenon behind the floating or sinking of any body. His theory later, influenced largely in designing air vehicles and more importantly, marine transport systems.
With the medium of Stellar Curiosity Workshop, SDRO aims to create the same scenario of scientific pursual among the children, making them enjoy their experiments as well as learn a great deal about how science works in the real world. SDRO brings this exclusive opportunity for the children and also for the elders to improvise different experiments and visualize what they had grasped through textbooks.