Question

Why threading is made on tyres?
Why rolling friction is less than sliding friction?
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Answer 1

Required Answer

Threading on tyres:

• The wheel would not roll on pushing it if there was no friction between the wheel and the ground.Thus, friction is desirable for wheels to roll over a surface. It is dangerous to drive on a wet road because the friction between the road and the tyres is very smal. This increases the chance of slipping the tyres from the road The threading on tyres is desianed to increase friction. Thus, threading improves road crin and makes it safer to drive even on wet road.

Rolling friction lesser than sliding friction:

• When the axle of a wheel is pushed, the force of friction between the wheel and the ground at the point of contact provides the reaction force. The reaction force acts at the contact points of the wheel in a direction opposite to the applied force. The wheel rolls without rupturing the cold welds. That is why the rolling friction is much smaller than sliding friction.The fact that rolling friction is less than sliding friction is applied in ball bearings or roller bearings to reduce losses due to friction.

Additional information:

Friction:

The force that oppose the motion of the moving object.

Rolling friction:

The force of friction between the rolling object and on which it rolls.

Sliding friction:

The force of friction between the sliding object and on which it slides.