Class 8 Physics Friction Friction - a necessary evil

(i) Desirable Friction - Grooves on Tyres       (ii) Undesirable Friction - Worn out soles

 

Desirable Friction

Undesirable Friction

These are the instances where friction exists and is absolutely essential

These are the instances where friction exists, but it is undesirable

Examples

· To bring a rolling ball to stop (else it would keep rolling)

·Grooves on automobile tyres increase friction between tyres and the rough road surface. They provide more grip

· Cleats on sports shoes provide better stability to the sportsman with the ground

· Rough sand paper is used to smooth wood

Examples

·Automobile parts, machine parts begin to  degrade over a period of time due to friction

·The sole of our shoes wears out after prolonged use because of friction with the rough road surface.

·When there are dry areas on a water slide, the slide fall will not be very smooth.

Such type of friction should be retained or increased

Such type of friction should beminimized

 

 

(Note: As we can see again, rough surfaces increase friction. Smooth surfaces decrease friction.)

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