Rolling Friction: Why Wheels are Used on Solid Surfaces

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Wheels are designed to reduce friction, making it easier to move objects across solid surfaces due to the lower rolling friction compared to sliding friction. However, wheels are ineffective in water because the friction is significantly less than on solid surfaces, negating the need for wheels. Instead, boats utilize streamlined shapes to minimize drag in water, similar to aircraft reducing air friction. The design of wheels, which relies on a single point of contact for rolling motion, is incompatible with the uniform forces acting on submerged wheels. Therefore, wheels are primarily used where higher friction exists to facilitate movement.
avito009
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You have to apply a force to counter the force of friction. In order to move fast the friction has to be reduced. So we have the invention of wheels. Rolling friction is much less than sliding friction. Experience shows that much less force is required to roll an object than to slide or drag it.

But wheels are not used in boats. why?

The friction on water is much less than that between solid surfaces. So because the friction is less the wheels can't be used.

So does that imply wheels are used when in contact with a surface where friction is more?.
 
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avito009 said:
You have to apply a force to counter the force of friction. In order to move fast the friction has to be reduced. So we have the invention of wheels. Rolling friction is much less than sliding friction. Experience shows that much less force is required to roll an object than to slide or drag it.

But wheels are not used in boats. why?

The friction on water is much less than that between solid surfaces. So because the friction is less the wheels can't be used.

So does that imply wheels are used when in contact with a surface where friction is more?.

Actually wheel has got a feature that only 1 point of it should be in contact with the surface so it can perform rollng motion which is in fact stop and go motion.but in case of boat the whole wheels remain inside water so wheel there is of no use there is use of streamlined body to decrease the friction just like how plane have streamlined shape to reduce air friction. thus there would be no use of wheel in water as forces and frictional forces would be acting uniformly at the frontal part of wheel. Thats the reason turbines are not submerged fully inside water. this is what i think hope you got it
 
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For simple comparison, I think the same thought process can be followed as a block slides down a hill, - for block down hill, simple starting PE of mgh to final max KE 0.5mv^2 - comparing PE1 to max KE2 would result in finding the work friction did through the process. efficiency is just 100*KE2/PE1. If a mousetrap car travels along a flat surface, a starting PE of 0.5 k th^2 can be measured and maximum velocity of the car can also be measured. If energy efficiency is defined by...

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