Fluid Friction

What are fluids?

We know that there are 3 forms of Matter

• Solids (Example - Ice)
• Liquids (Example - Water)
• Gases (Example-Water Vapour)

Fluid is the common name given to liquid and gases

Is force of friction only exerted by solids?

No

It is exerted by all forms of matter-solids or fluids(liquid and gases)

What is fluid friction

Frictional force exerted by liquids and gases is called fluid friction

It is also called Drag or Drag Force

Example 1

When an aeroplane flies in air,it faces resistance from air which reduces its speed

This air resistance is frictional force of air or fluid friction

Example 2

When a speedboat moves in sea,it faces resistance from water in the sea which reduces its speed

This is frictional force of water or fluid friction

Factors which Effect Fluid Friction

Speed of Object

More the speed of object,more will be fluid friction.Less the speed ,less the fluid friction

Example A speed boat will face more friction compared to a paddle boat

Shape of Object

If object is streamline(pointed from front),they face less fluid friction

But if object is not streamlined,it faces more friction

Example - A truck will face more friction compared to a car

Size of Object

larger the size of object,more the friction

Smaller the size,less the friction

Example - A ship will face more friction compared to a boat

Nature of fluid

If fluid is more viscous or thick,there will be more friction 

If fluid is less viscous or thin,there will be less fiction

Example - Water is thicker than air,so there is more friction in water compared to air.This is why aeroplanes move faster than ships

Why it is important to reduce fluid friction?

It is important to reduce fluid friction because

Reduces Speed

Fluid friction reduces speed of vehicle.(If there was no friction,vehicle would move faster)

Increase Costs

it reduces efficiency and increase cost of running vehicle(More fuel is required to overcome fluid resistance)

How to Reduce Fluid Friction?

Fluid friction is reduced by streamlining shape of vehicle

This is done by making it pointed from front like a bird

Also wings are provided in case of aeroplane

This help in reducing air resistance and increasing speed and efficiency of object

Example 1

Front of Aeroplanes are pointed .They also have wings,This reduces friction in air and make aeroplane travel faster

Example 2

Boats and Ships are also pointed in front.This reduce friction in water

Example 3

Similarly, car is also streamlined to reduce air resistance (or drag)