Explain why objects moving in fluids must have special shapes.

Hint – In this question use the concept that when a body is made to move in a fluid medium then the fluid exert a force exactly in the opposite direction of its motion. This force may be due to viscosity of the fluid or is dependent upon many other features. Use this concept to comment why the shape is made in different configurations.

Complete Step-by-Step solution:
When a body moves through a fluid, it experiences an opposing force which tries to oppose its motion through the fluid.
The opposing force is called the drag force or frictional force.
This frictional force depends on the shape of the body.
So if we give objects a special shape, the force of friction or drag force acting on it can be minimized.
Hence, it becomes easier for the body to move comfortably through the fluid, if the shape of the body is irregular than the friction force or drag force is maximum and the shape does not move comfortably in the fluid.
Hence objects moving in the fluids must have special shapes.
So this is the required answer.

Note – In every good example that bodies moving inside fluid have special shapes is the submarine. Modern submarines are cigar-shaped. The design of the early submarines was also special and is known as “teardrop hull”. The reason behind such shapes is that it reduces the hydrodynamic drag when submerged but however every aspect has advantage and disadvantage thus similarly this decreases the sea-keeping capabilities and drag while surfaced.