FRICTION_TYPES-Advantages_Disadvantages_BookerAgency

 FRICTION

⦁ When you through a ball why does it come to rest?

⦁ When we kick a ball and a box with same force why the ball covers more distance? 

⦁ Well! in previous grades you came to know that friction helps us walk easily, it prevents from sliding but sometimes it has disadvantages as well.  

⦁ Friction is a contact force caused by the roughness or deformation of the materials in contact.

⦁ The frictional force between a wooden block and cemented floor caused by the roughness of both the surfaces is projected .

⦁ Frictional forces are always parallel to the plane of contact between two surfaces and opposite to the direction of the applied force FRICTION

⦁ Friction is self adjusting. It can increase to a certain value known as limiting force (F).

⦁ It is proportional to s normal force R.

⦁    F  directly proportional to R 

⦁ The ratio between limiting force and normal reaction R is constant that is represented by coefficient of friction.

TYPES

⦁ Static friction

⦁ It is force acting on an object at rest that resists its ability to start moving. The maximum static friction is known as “limiting friction”

⦁ Kinetic friction

⦁ It is the force that resists  the motion of a moving object. It is interesting to know that in almost all situations, static friction is greater than kinetic friction.

⦁ Sliding friction

⦁ When one body slides over the other body the friction between two surfaces is said to be sliding friction.

⦁ Rolling friction

⦁ When a body moves on wheels the friction is said to be rolling friction. Rolling friction is much lesser than the sliding friction

Advantages of Friction

⦁ Friction enables us to walk on ground. 

⦁ Friction protects from sliding, as sand is thrown to maintain friction on inclined railway tracks during rain. 

⦁ The car brakes slow down the car to stop safely. 

⦁ Threads and grooves are designed on tyres to increase the friction and improve grip between road and wheel .

⦁ Now vehicles are equipped with Anti-lock Braking System (ABS). 

⦁ ABS is designed to maintain  steering stability, improve vehicle control, avoid skidding and decreases stopping distances on dry and slippery surfaces.

⦁ The ABS maintains the static friction as the wheel starts slipping it releases the brake automatically for a fraction of a second then holds wheel again to create static friction between road and tyres 

Disadvantages of Friction

⦁ A large amount of energy is wasted in the machines due to friction. Friction leads to wear and tear of parts hence increases the service cost. Failure of oil pump in car engine results contact between dry metals which yields high temperature hence the car engine is seized

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Ways to reduce Friction

⦁ Wheels, pullies, ball bearings, lubricants and graphite are used to overcome the friction

⦁ Lubricating the motor axel,

⦁ sewing machine and bicycle chain reduces friction and prevents wear and tear.

⦁ The shape of vehicle is also designed to reduce air resistance.