Operation “Diya Kawa”; The physics beneath it

The annual joint war exercise by the three forces is the “cormorant strike”. This operation is based on the aquatic bird cormorant, commonly known as “Diya kawa”

The Diya Kawa uses many of the principles of physics from up thrust to conservation of energy. In this article I thought of uncovering the physics beneath the “Diya Kawa” which is the basis of this military operation

This bird, a predator catching fish in the ocean is mostly seen gliding over the water surface. It does not flap its wings yet remains floating. How does it do this? The answer is simple. The law of floatation used by us in fluid dynamics is used here. The up thrust exerted on the bird by the air supports its weight. Thus the bird floats much like a cork floating on water

On close observation it is noted that this intelligent bird rarely misses its prey unlike other aquatic birds. Once the prey is identified, it calculates the real depth to the fish from the water surface using laws of refraction.

Then it gains sufficient height to gain sufficient potential energy for its strike. As it comes down, the body is shaped into a streamlined position to reduce air resistance. It flies with great speed converting most of its potential energy to kinetic energy at the water surface

As it enters the water not a drop of water splashes, confirming that it enters the water at the most accurate angle to gain a maximum depth of about 150 ft. then it dives in and captures the prey

Before entering the water it traps air inside its wings and curls into a ball. The maximum up thrust exerted due to this helps it to return to the water surface easily

Isn’t it amazing how even a bird can teach us many physics principles? Mother Nature holds many surprises. Be prepared to unfold them.

By Rukmanthi Fernando