Question

In which of the following examples does streamlining help in reducing friction?

• A. Fish
  
• B. Aeroplane
  
• C. Bird
  
• D. Satellite
  

Answer 1

Answer: (A), (B), (C)

Bird


Picture A, an aeroplane faces air resistance or air drag when it flies through air.
Picture C, a bird also in a similar way has to overcome air resistance when it flies.
Picture D, a fish has to push its way through all the water around it and hence faces water resistance.
Streamlining is a process of giving such a shape to a body that has minimum resistance towards fluids like air and water.
Birds and fishes naturally have streamlined bodies to reduce the air or water resistance and help them move faster.
But picture B, a satellite, does not face any such resistance because it moves through space which contains no air. So it will not face any such resistance because of fluids around it and doesn’t need streamlining.
So in case of an aeroplane, a bird and a fish, streamlining helps in reducing friction but in case of a satellite it is unnecessary as friction with the surrounding medium is absent.