What is friction|Types of friction| How to increase or decrease friction

Friction 

Content

     1:- What is friction 

     2:- Direction of friction 

     3:- Cause of Friction

     4:- Types of friction

     5:- Advantages of friction

     6:- Disadvantages of friction

     7:- Some ways to reduce friction

     8:- Some ways to reduce friction

1:- Friction

       Friction is a phenomenon due to which there is a force that resist the motion of objects, relative to each other when the objects are in content. 

Friction changes kinetic energy to heat. Over time, friction slows down motion and stops it. 

2:- Direction of force 

         The force of friction acts in a direction opposite to the direction in which an objects moves (or tends to move). 

Force of friction is measured in newtons, just likes other forces. The force of friction also referred to as simply 'friction'.

The grocery of friction is always present, when surfaces touches another. 

Direction of Friction

3:- Cause of Friction

         All friction occurs because all the objects have rough Surfaces. Their microscopic examination mould reveal that all these surfaces have irregularities (hills and valley). The force of friction is caused by the interlocking of the irregularities of the two surfaces. 

Friction between two surfaces depends of the following  factors. 

   1- Nature of the surface in contact. Friction is greater between rough surfaces than between smooth ones. 

   2- Normal force that acts on the body. 

Thus the friction between a lighter object and floor is less that that between a heavier object and the floor. 

   3- Nature of the motion of the body  (rolling or sliding). 

Note : the friction does not depend on the amount of surface area if the region of contact of the two objects.

4:-Types of friction

     Kinetic friction :- It is the friction which exist between moving bodies. The amount of kinetic friction between two surfaces depends partly on how the surfaces move. Kinetic friction is of two types. 

   a)-  Sliding friction :- It is the frictional force present when 

   b)-  Sliding friction :- It is the frictional force present when one body moves slowly        (i.e. slides) over  the surface of another object. 

Usually, the force of sliding kinetic friction is greater than the force of rolling kinetic friction. This is reason why it is easier to move objects on wheels than to slide the objects along the floor. 

    Static friction :-  It occurs when a force is applied to an object but is not able to move the object. The object does not move because the force of static friction balances the force applied. Static friction can be overcome by applying large enough force. Static friction as soon as the object starts moving and then kinetic energy immediately comes to play. 

    Fluid resistance:- Friction occurs in fluid. A fluid is anything that flows like air or water. The friction force which resists the movement of an object moving through a fluid is called drag. 

  

   Streamlining:- Drag which slows down the motion of an object such as boat can be reduced by Streamlining the shape of the object. Streamlined shapes such as those of birds, fishes, etc. Are narrow in front and sloping from sides. 

5:- Advantages of friction

   1:- It enables us to walk without slipping

   2:- It enables a vehicle to move forward on road without skidding. 

   3:- It enables us to apply brakes and slow down or stop a moving vehicle. 

   4:- It enables us to write and draw on paper. 

   5:- It enables us to pick up and hold things in our hand 

   6:- It enables us to fix nails in a wall or wood. 

   7:- It enables us to light a match stick. 

   8:- It enables us to cut wood with a saw. 

6:- Disadvantages of Friction

     1:- Friction between moving parts of an engine increases their temperature and causes the parts to wear down coolant has to be added to the engine to prevent the engine for overheating. 

     2:- It wears out the rubbing machine parts, the tyres of vehicles, the brake pads of vehicles, the roles of our show and many many other objects. 

7:- Some ways to Reduce Friction

    1:- By using lubricant– These are applied to reduce the friction between the surfaces, Some example of lubricant are motor oil, wax and grease. 

    2:- By switching from sliding kinetic friction to rolling kinetic friction– Ball bearings placed between the wheel and axles of in-line Skates and bicycles make it easier for the wheels to turn by reducing friction. 

    3:- By making surfaces that rub against each other smoother by polishing – 

 For example, a wooden partay ne made smoother by rubbing with a sandpaper and thus made  comfortable to sit on. 

6:- Some ways to Increase Friction 

    1:- By making surfaces to rougher. 

 For example, vehicles on wet or icy roads may skid and also on wet mud the wheel may move round without moving ahead. Sand and gravel (small pebbles) are scattered to overcome this situations. 

   

   2:- By increasing the force pushing the surface together. For example, sanding of wood may be done faster by pressing harder the sand paper. 

    

  3:- By making grooves in the soles of shoes to prevent slipping. 

  

  4:- By treating the tyres it prevent skidding of the vehicles. 

  

  5:- By providing spikes in the shoes of players and athletes. 

  

  6:- By applying some coarse substance in hand to increase friction cor better grip 

  7:- By making machine bolts of special materials which increase friction so that the bolts can drive machine without slipping. 

  

   

 

        

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